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khan-exercise.js
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khan-exercise.js
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/* khan-exercise.js
The main entry point here is actually the loadScripts method which is defined
as Khan.loadScripts and then evaluated around line 500.
When this loadScripts is called, it loads in many of the pre-reqs and then
calls, one way or another, setUserExercise concurrently with loadModules.
setProblemNum updates some instance vars that get looked at by other functions.
loadModules takes care of loading an individual exercise's prereqs (i.e.
word problems, etc). It _also_ loads in the khan academy site skin and
exercise template via injectSite which runs prepareSite first then
makeProblemBag and makeProblem when it finishes loading dependencies.
pepareSite and makeProblem are both fairly heavyweight functions.
If you are trying to register some behavior when the page loads, you
probably want it to go in prepareSite. (which also registers server-initiated
behavior via api.js) as well. By the time prepareSite is called, jquery and
any core plugins are already available.
If you are trying to do something each time a problem loads, you probably
want to look at makeProblem.
At the end of evaluation, the inner Khan object is returned/exposed as well
as the inner Util object.
Catalog of events fired on the Khan object by khan-exercises:
* newProblem -- when a new problem has completely finished rendering
* hintUsed -- when a hint has been used by the user
* allHintsUsed -- when all possible hints have been used by the user
* checkAnswer -- when the user attempts to check an answer, incorrect or
correct
* problemDone -- when the user has completed a problem which, in this case,
usually means supplying the correct answer
* attemptSaved -- when an attempt has been recorded successfully via the
API
* attemptError -- when an error occurs during an API attempt
* apiRequestStarted / apiRequestEnded -- when an API request is sent
outbound or completed, respectively. Listeners can keep track of whether
or not khan-exercises is still waiting on API responses.
* exerciseLoaded:[exercise-name] -- when an exercise and all of its
dependencies are loaded and ready to render
* updateUserExercise -- when an updated userExercise has been received
and is being used by khan-exercises, either via the result of an API
call or initialization
*/
var Khan = (function() {
function warn(message, showClose) {
$(function() {
var warningBar = $("#warning-bar");
$("#warning-bar-content").html(message);
if (showClose) {
warningBar.addClass("warning")
.children("#warning-bar-close").show();
} else {
warningBar.addClass("error")
.children("#warning-bar-close").hide();
}
warningBar.fadeIn("fast");
});
}
// Prime numbers used for jumping through exercises
var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43,
47, 53, 59, 61, 67, 71, 73, 79, 83],
/*
===============================================================================
Crc32 is a JavaScript function for computing the CRC32 of a string
...............................................................................
Version: 1.2 - 2006/11 - http://noteslog.com/category/javascript/
-------------------------------------------------------------------------------
Copyright (c) 2006 Andrea Ercolino
http://www.opensource.org/licenses/mit-license.php
===============================================================================
*/
// CRC32 Lookup Table
table = "00000000 77073096 EE0E612C 990951BA 076DC419 706AF48F E963A535 " +
"9E6495A3 0EDB8832 79DCB8A4 E0D5E91E 97D2D988 09B64C2B 7EB17CBD " +
"E7B82D07 90BF1D91 1DB71064 6AB020F2 F3B97148 84BE41DE 1ADAD47D " +
"6DDDE4EB F4D4B551 83D385C7 136C9856 646BA8C0 FD62F97A 8A65C9EC " +
"14015C4F 63066CD9 FA0F3D63 8D080DF5 3B6E20C8 4C69105E D56041E4 " +
"A2677172 3C03E4D1 4B04D447 D20D85FD A50AB56B 35B5A8FA 42B2986C " +
"DBBBC9D6 ACBCF940 32D86CE3 45DF5C75 DCD60DCF ABD13D59 26D930AC " +
"51DE003A C8D75180 BFD06116 21B4F4B5 56B3C423 CFBA9599 B8BDA50F " +
"2802B89E 5F058808 C60CD9B2 B10BE924 2F6F7C87 58684C11 C1611DAB " +
"B6662D3D 76DC4190 01DB7106 98D220BC EFD5102A 71B18589 06B6B51F " +
"9FBFE4A5 E8B8D433 7807C9A2 0F00F934 9609A88E E10E9818 7F6A0DBB " +
"086D3D2D 91646C97 E6635C01 6B6B51F4 1C6C6162 856530D8 F262004E " +
"6C0695ED 1B01A57B 8208F4C1 F50FC457 65B0D9C6 12B7E950 8BBEB8EA " +
"FCB9887C 62DD1DDF 15DA2D49 8CD37CF3 FBD44C65 4DB26158 3AB551CE " +
"A3BC0074 D4BB30E2 4ADFA541 3DD895D7 A4D1C46D D3D6F4FB 4369E96A " +
"346ED9FC AD678846 DA60B8D0 44042D73 33031DE5 AA0A4C5F DD0D7CC9 " +
"5005713C 270241AA BE0B1010 C90C2086 5768B525 206F85B3 B966D409 " +
"CE61E49F 5EDEF90E 29D9C998 B0D09822 C7D7A8B4 59B33D17 2EB40D81 " +
"B7BD5C3B C0BA6CAD EDB88320 9ABFB3B6 03B6E20C 74B1D29A EAD54739 " +
"9DD277AF 04DB2615 73DC1683 E3630B12 94643B84 0D6D6A3E 7A6A5AA8 " +
"E40ECF0B 9309FF9D 0A00AE27 7D079EB1 F00F9344 8708A3D2 1E01F268 " +
"6906C2FE F762575D 806567CB 196C3671 6E6B06E7 FED41B76 89D32BE0 " +
"10DA7A5A 67DD4ACC F9B9DF6F 8EBEEFF9 17B7BE43 60B08ED5 D6D6A3E8 " +
"A1D1937E 38D8C2C4 4FDFF252 D1BB67F1 A6BC5767 3FB506DD 48B2364B " +
"D80D2BDA AF0A1B4C 36034AF6 41047A60 DF60EFC3 A867DF55 316E8EEF " +
"4669BE79 CB61B38C BC66831A 256FD2A0 5268E236 CC0C7795 BB0B4703 " +
"220216B9 5505262F C5BA3BBE B2BD0B28 2BB45A92 5CB36A04 C2D7FFA7 " +
"B5D0CF31 2CD99E8B 5BDEAE1D 9B64C2B0 EC63F226 756AA39C 026D930A " +
"9C0906A9 EB0E363F 72076785 05005713 95BF4A82 E2B87A14 7BB12BAE " +
"0CB61B38 92D28E9B E5D5BE0D 7CDCEFB7 0BDBDF21 86D3D2D4 F1D4E242 " +
"68DDB3F8 1FDA836E 81BE16CD F6B9265B 6FB077E1 18B74777 88085AE6 " +
"FF0F6A70 66063BCA 11010B5C 8F659EFF F862AE69 616BFFD3 166CCF45 " +
"A00AE278 D70DD2EE 4E048354 3903B3C2 A7672661 D06016F7 4969474D " +
"3E6E77DB AED16A4A D9D65ADC 40DF0B66 37D83BF0 A9BCAE53 DEBB9EC5 " +
"47B2CF7F 30B5FFE9 BDBDF21C CABAC28A 53B39330 24B4A3A6 BAD03605 " +
"CDD70693 54DE5729 23D967BF B3667A2E C4614AB8 5D681B02 2A6F2B94 " +
"B40BBE37 C30C8EA1 5A05DF1B 2D02EF8D",
/* Number */
crc32 = function(str, crc) {
if (crc == window.undefined) {
crc = 0;
}
var n = 0; //a number between 0 and 255
var x = 0; //a hex number
crc = crc ^ (-1);
for (var i = 0, iTop = str.length; i < iTop; i++) {
n = (crc ^ str.charCodeAt(i)) & 0xFF;
x = "0x" + table.substr(n * 9, 8);
crc = (crc >>> 8) ^ x;
}
return Math.abs(crc ^ (-1));
},
userExercise = undefined,
// Check to see if we're in test mode
testMode = typeof Exercises === "undefined",
// The main server we're connecting to for saving data
server = typeof apiServer !== "undefined" ? apiServer :
testMode ? "http://localhost:8080" : "",
// The name of the exercise -- this will only be set here in testMode
exerciseName = ((/([^\/.]+)(?:\.html)?$/.exec(window.location.pathname) || [])[1]),
// Bin users into a certain number of realms so that
// there is some level of reproducability in their questions
bins = 200,
// The seed information
randomSeed,
// Holds the current username
user = null,
userCRC32,
// The current problem and its corresponding exercise
problem,
exercise,
// The number of the current problem that we're on
problemNum = 1,
// Info for constructing the seed
seedOffset = 0,
jumpNum = 1,
problemSeed = 0,
problemID,
// The current validator function
validator,
hints,
// The exercise elements
exercises,
// Where we are in the shuffled list of problem types
problemBag,
problemBagIndex = 0,
// How many problems are we doing? (For the fair shuffle bag.)
problemCount = 10,
// For saving problems to the server
hintsUsed,
lastAction,
attempts,
guessLog,
userActivityLog,
// A map of jQuery queues for serially sending and receiving AJAX requests.
requestQueue = {},
// Debug data dump
dataDump = {
"exercise": exerciseName,
"problems": [],
"issues": 0
},
// Dict of exercise names that are loading.
// Values are number of remote exercises that are currently
// pending in the middle of a load.
loadingExercises = {},
urlBase = typeof urlBaseOverride !== "undefined" ? urlBaseOverride :
testMode ? "../" : "/khan-exercises/",
lastFocusedSolutionInput = null,
issueError = "Communication with GitHub isn't working. Please file "
+ "the issue manually at <a href=\""
+ "http://github.com/Khan/khan-exercises/issues/new\">GitHub</a>. "
+ "Please reference exercise: " + exerciseName + ".",
issueSuccess = function(url, title, suggestion) {
return ["Thank you for your feedback! Your issue has been created and can be ",
"found at the following link:",
"<p><a id=\"issue-link\" href=\"", url, "\">", title, "</a>",
"<p>", suggestion, "</p>"].join("");
},
issueIntro = "Remember to check the hints and double check your math. All provided information will be public. Thanks for your help!",
// True once we've sent a request to load all modules
modulesLoaded = false,
// jQuery.Deferred object that registers
// callbacks to be run when all modules are done
// loading.
modulesDeferred = null,
gae_bingo = window.gae_bingo || { bingo: function() {} },
// The ul#examples (keep in a global because we need to modify it even when it's out of the DOM)
examples = null;
// Add in the site stylesheets
if (testMode) {
(function() {
var link = document.createElement("link");
link.rel = "stylesheet";
link.href = urlBase + "css/khan-site.css";
document.getElementsByTagName("head")[0].appendChild(link);
link = document.createElement("link");
link.rel = "stylesheet";
link.href = urlBase + "css/khan-exercise.css";
document.getElementsByTagName("head")[0].appendChild(link);
})();
}
// The main Khan Module
var Khan = {
modules: {},
// So modules can use file paths properly
urlBase: urlBase,
moduleDependencies: {
"math": [{
src: urlBase + "utils/MathJax/1.1a/MathJax.js?config=KAthJax-a5c67e8a5046db2ff8dfc2229a228836"
}, "raphael"],
// Load Raphael locally because IE8 has a problem with the 1.5.2 minified release
// http://groups.google.com/group/raphaeljs/browse_thread/thread/c34c75ad8d431544
// The normal module dependencies.
"calculus": ["math", "expressions", "polynomials"],
"exponents": ["math", "math-format"],
"kinematics": ["math"],
"math-format": ["math", "expressions"],
"polynomials": ["math", "expressions"],
"stat": ["math"],
"word-problems": ["math"],
"derivative-intuition": ["jquery.mobile.vmouse"],
"unit-circle": ["jquery.mobile.vmouse"],
"interactive": ["jquery.mobile.vmouse"],
"mean-and-median": ["stat"],
"math-model": ["ast"],
"simplify": ["math-model", "ast", "expr-helpers", "expr-normal-form", "steps-helpers"]
},
warnTimeout: function() {
warn("Your internet might be too slow to see an exercise. Refresh the page "
+ 'or <a href="" id="warn-report">report a problem</a>.', false);
$("#warn-report").click(function(e) {
e.preventDefault();
$("#report").click();
});
},
warnFont: function() {
var enableFontDownload = "enable font download in your browser";
if ($.browser.msie) {
enableFontDownload = '<a href="http://missmarcialee.com/2011/08/how-to-enable-font-download-in-internet-explorer-8/" target="_blank">enable font download</a>';
}
warn("You should " + enableFontDownload + " to improve the appearance of math expressions.", true);
},
require: function(mods) {
if (mods == null) {
return;
} else if (typeof mods === "string") {
mods = mods.split(" ");
} else if (!$.isArray(mods)) {
mods = [mods];
}
$.each(mods, function(i, mod) {
var src, deps;
if (typeof mod === "string") {
var cachebust = "";
if (testMode && Khan.query.nocache != null) {
cachebust = "?" + Math.random();
}
src = urlBase + "utils/" + mod + ".js" + cachebust;
deps = Khan.moduleDependencies[mod];
mod = {
src: src,
name: mod
};
} else {
src = mod.src;
deps = mod.dependencies;
delete mod.dependencies;
}
if (!Khan.modules[src]) {
Khan.modules[src] = mod;
Khan.require(deps);
}
});
},
// Populate this with modules
Util: {
// http://burtleburtle.net/bob/hash/integer.html
// This is also used as a PRNG in the V8 benchmark suite
random: function() {
// Robert Jenkins' 32 bit integer hash function.
var seed = randomSeed;
seed = ((seed + 0x7ed55d16) + (seed << 12)) & 0xffffffff;
seed = ((seed ^ 0xc761c23c) ^ (seed >>> 19)) & 0xffffffff;
seed = ((seed + 0x165667b1) + (seed << 5)) & 0xffffffff;
seed = ((seed + 0xd3a2646c) ^ (seed << 9)) & 0xffffffff;
seed = ((seed + 0xfd7046c5) + (seed << 3)) & 0xffffffff;
seed = ((seed ^ 0xb55a4f09) ^ (seed >>> 16)) & 0xffffffff;
return (randomSeed = (seed & 0xfffffff)) / 0x10000000;
}
},
// Load in a collection of scripts, execute callback upon completion
loadScripts: function(urls, callback) {
var loaded = 0,
loading = urls.length,
head = document.getElementsByTagName("head")[0];
callback || (callback = function() {});
for (var i = 0; i < loading; i++) { (function(mod) {
var isMathJax = mod.src.indexOf("/MathJax/") !== -1,
onScriptLoad = function() {
// Bump up count of scripts loaded
loaded++;
// Run callback in case we're finished loading all
// modules
runCallback();
};
if (!testMode && mod.src.indexOf("/khan-exercises/") === 0 && !isMathJax) {
// Don't bother loading khan-exercises content in production
// mode, this content is already packaged up and available
// (*unless* it's MathJax, which is silly still needs to be loaded)
loaded++;
return;
}
// Adapted from jQuery getScript (ajax/script.js)
var script = document.createElement("script");
script.async = "async";
for (var prop in mod) {
script[prop] = mod[prop];
}
script.onerror = function() {
// No error in IE, but this is mostly for debugging during development so it's probably okay
// http://stackoverflow.com/questions/2027849/how-to-trigger-script-onerror-in-internet-explorer
Khan.error("Error loading script " + script.src);
};
script.onload = script.onreadystatechange = function() {
if (!script.readyState || (/loaded|complete/).test(script.readyState)) {
// Handle memory leak in IE
script.onload = script.onreadystatechange = null;
// Remove the script
if (script.parentNode) {
script.parentNode.removeChild(script);
}
// Dereference the script
script = undefined;
if (isMathJax) {
// If we're loading MathJax, don't bump up the
// count of loaded scripts until MathJax is done
// loading all of its dependencies.
MathJax.Hub.Queue(onScriptLoad);
} else {
onScriptLoad();
}
}
};
head.appendChild(script);
})(urls[i]); }
runCallback();
function runCallback() {
if (callback && loading === loaded) {
callback();
}
}
},
// Query String Parser
// Original from:
// http://stackoverflow.com/questions/901115/get-querystring-values-in-javascript/2880929#2880929
queryString: function() {
var urlParams = {},
e,
a = /\+/g, // Regex for replacing addition symbol with a space
r = /([^&=]+)=?([^&]*)/g,
d = function(s) { return decodeURIComponent(s.replace(a, " ")); },
q = window.location.search.substring(1);
while ((e = r.exec(q))) {
urlParams[d(e[1])] = d(e[2]);
}
return urlParams;
},
// Display error messages
error: function() {
if (typeof console !== "undefined") {
$.each(arguments, function(ix, arg) {
console.error(arg);
});
}
},
scratchpad: (function() {
var disabled = false, wasVisible, pad;
var actions = {
disable: function() {
wasVisible = actions.isVisible();
actions.hide();
$("#scratchpad-show").hide();
$("#scratchpad-not-available").show();
disabled = true;
},
enable: function() {
if (wasVisible) {
actions.show();
wasVisible = false;
}
$("#scratchpad-show").show();
$("#scratchpad-not-available").hide();
disabled = false;
},
isVisible: function() {
return $("#scratchpad").is(":visible");
},
show: function() {
if (actions.isVisible()) {
return;
}
var makeVisible = function() {
$("#workarea, #hintsarea").css("padding-left", 60);
$("#scratchpad").show();
$("#scratchpad-show").text("Hide scratchpad");
// If pad has never been created or if it's empty
// because it was removed from the DOM, recreate a new
// scratchpad.
if (!pad || !$("#scratchpad div").children().length) {
pad = new Scratchpad($("#scratchpad div")[0]);
}
};
if (!pad) {
Khan.loadScripts([{src: urlBase + "utils/scratchpad.js"}], makeVisible);
} else {
makeVisible();
}
},
hide: function() {
if (!actions.isVisible()) {
return;
}
$("#workarea, #hintsarea").css("padding-left", 0);
$("#scratchpad").hide();
$("#scratchpad-show").text("Show scratchpad");
},
toggle: function() {
actions.isVisible() ? actions.hide() : actions.show();
},
clear: function() {
if (pad) {
pad.clear();
}
},
resize: function() {
if (pad) {
pad.resize();
}
}
};
return actions;
})(),
relatedVideos: {
exercise: null,
cache: {},
getVideos: function() {
return this.cache[this.exercise.name] || [];
},
setVideos: function(exercise) {
if (exercise.relatedVideos) {
this.cache[exercise.name] = exercise.relatedVideos;
}
this.exercise = exercise;
this.render();
},
showThumbnail: function(index) {
$("#related-video-list .related-video-list li").each(function(i, el) {
if (i === index) {
$(el)
.find("a.related-video-inline").hide().end()
.find(".thumbnail").show();
}
else {
$(el)
.find("a.related-video-inline").show().end()
.find(".thumbnail").hide();
}
});
},
// make a link to a related video, appending exercise ID.
makeHref: function(video) {
return video.relativeUrl + "?exid=" + this.exercise.name;
},
anchorElement: function(video, needComma) {
var template = Templates.get("video.related-video-link");
return $(template({
href: this.makeHref(video),
video: video,
separator: needComma
})).data("video", video);
},
renderInSidebar: function() {
var container = $(".related-video-box");
var jel = container.find(".related-video-list");
jel.empty();
var template = Templates.get("video.thumbnail");
_.each(this.getVideos(), function(video, i) {
var thumbnailDiv = $(template({
href: this.makeHref(video),
video: video
})).find("a.related-video").data("video", video).end();
var inlineLink = this.anchorElement(video)
.addClass("related-video-inline");
var sideBarLi = $("<li>")
.append(inlineLink)
.append(thumbnailDiv);
if (i > 0) {
thumbnailDiv.hide();
} else {
inlineLink.hide();
}
jel.append(sideBarLi);
}, this);
container.toggle(this.getVideos().length > 0);
},
hookup: function() {
// make caption slide up over the thumbnail on hover
var captionHeight = 45;
var marginTop = 23;
// queue:false to make sure these run simultaneously
var options = {duration: 150, queue: false};
$(".related-video-box")
.delegate(".thumbnail", "mouseenter mouseleave", function(e) {
var el = $(e.currentTarget);
if (e.type == "mouseenter") {
el.find(".thumbnail_label").animate(
{marginTop: marginTop},
options)
.end()
.find(".thumbnail_teaser").animate(
{height: captionHeight},
options)
.end();
} else {
el.find(".thumbnail_label").animate(
{marginTop: marginTop + captionHeight},
options)
.end()
.find(".thumbnail_teaser").animate(
{height: 0},
options)
.end();
}
});
},
render: function() {
// don't try to render if templates aren't present (dev mode)
if (!window.Templates) return;
this.renderInSidebar();
}
},
showSolutionButtonText: function() {
return hintsUsed ? "Show step (" + hints.length + " left)" : "Show Solution";
}
};
// see line 183. this ends the main Khan module
// Load query string params
Khan.query = Khan.queryString();
if (Khan.query.activity !== undefined) {
userExercise = {
current: true,
exerciseModel: {},
readOnly: true,
userActivity: JSON.parse(Khan.query.activity)
};
}
// Seed the random number generator with the user's hash
randomSeed = testMode && parseFloat(Khan.query.seed) || userCRC32 || (new Date().getTime() & 0xffffffff);
// Load in jQuery
var scripts = (typeof jQuery !== "undefined") ? [] : [{src: "../jquery.js"}];
// Actually load the scripts. This is getting evaluated when the file is loaded.
Khan.loadScripts(scripts, function() {
if (testMode) {
Khan.require(["../jquery-ui"]);
}
// Base modules required for every problem
Khan.require(["answer-types", "tmpl", "underscore", "jquery.adhesion", "hints"]);
Khan.require(document.documentElement.getAttribute("data-require"));
// Initialize to an empty jQuery set
exercises = jQuery();
$(function() {
var remoteExercises = $("div.exercise[data-name]");
if (remoteExercises.length) {
remoteExercises.each(loadExercise);
// Only run loadModules if exercises are in the page
} else if ($("div.exercise").length) {
loadModules();
}
});
$.fn.extend({
// Pick a random element from a set of elements
getRandom: function() {
return this.eq(Math.floor(this.length * KhanUtil.random()));
},
// Run the methods provided by a module against some elements
runModules: function(problem, type) {
type = type || "";
var info = {
testMode: testMode
};
return this.each(function(i, elem) {
elem = $(elem);
// Run the main method of any modules
$.each(Khan.modules, function(src, mod) {
var name = mod.name;
if ($.fn[name + type]) {
elem[name + type](problem, info);
}
});
});
}
});
// See if an element is detached
$.expr[":"].attached = function(elem) {
return $.contains(elem.ownerDocument.documentElement, elem);
};
});
// Add up how much total weight is in each exercise so we can adjust for
// it later
function weighExercises(problems) {
if (exercises.length > 1) {
$.map(problems, function(elem) {
elem = $(elem);
var exercise = elem.parents("div.exercise").eq(0);
var exerciseTotal = exercise.data("weight-sum");
exerciseTotal = exerciseTotal !== undefined ? exerciseTotal : 0;
var weight = elem.data("weight");
weight = weight !== undefined ? weight : 1;
exercise.data("weight-sum", exerciseTotal + weight);
});
}
}
// Create a set of n problems fairly from the weights - not random; it
// ensures that the proportions come out as fairly as possible with ints
// (still usually a little bit random).
// There has got to be a better way to do this.
function makeProblemBag(problems, n) {
var bag = [], totalWeight = 0;
if (testMode && Khan.query.test != null) {
// Just do each problem 10 times
$.each(problems, function(i, elem) {
elem = $(elem);
elem.data("id", elem.attr("id") || "" + i);
for (var j = 0; j < 10; j++) {
bag.push(problems.eq(i));
}
});
problemCount = bag.length;
} else if (problems.length > 0) {
// Collect the weights for the problems and find the total weight
var weights = $.map(problems, function(elem, i) {
elem = $(elem);
var exercise = elem.parents("div.exercise").eq(0);
var exerciseWeight = exercise.data("weight");
exerciseWeight = exerciseWeight !== undefined ? exerciseWeight : 1;
var exerciseTotal = exercise.data("weight-sum");
var weight = elem.data("weight");
weight = weight !== undefined ? weight : 1;
if (exerciseTotal !== undefined) {
weight = weight * exerciseWeight / exerciseTotal;
elem.data("weight", weight);
}
// Also write down the index/id for each problem so we can do
// links to problems (?problem=17)
elem.data("id", elem.attr("id") || "" + i);
totalWeight += weight;
return weight;
});
while (n) {
bag.push((function() {
// Figure out which item we're going to pick
var index = totalWeight * KhanUtil.random();
for (var i = 0; i < problems.length; i++) {
if (index < weights[i] || i === problems.length - 1) {
var w = Math.min(weights[i], totalWeight / (n--));
weights[i] -= w;
totalWeight -= w;
return problems.eq(i);
} else {
index -= weights[i];
}
}
// This will never happen
return Khan.error("makeProblemBag got confused w/ index " + index);
})());
}
}
return bag;
}
function enableCheckAnswer() {
$("#check-answer-button")
.removeAttr("disabled")
.removeClass("buttonDisabled")
.val("Check Answer");
}
function disableCheckAnswer() {
$("#check-answer-button")
.attr("disabled", "disabled")
.addClass("buttonDisabled")
.val("Please wait...");
}
function isExerciseLoaded(exerciseName) {
return _.any(exercises, function(exercise) {
return $.data(exercise, "rootName") === exerciseName;
});
}
function startLoadingExercise(exerciseName) {
if (typeof loadingExercises[exerciseName] !== "undefined") {
// Already started loading this exercise.
return;
}
if (isExerciseLoaded(exerciseName)) {
return;
}
var exerciseElem = $("<div>")
.data("name", exerciseName)
.data("rootName", exerciseName);
// Queue up an exercise load
loadExercise.call(exerciseElem, function() {
// Trigger load completion event for this exercise
$(Khan).trigger("exerciseLoaded:" + exerciseName);
delete loadingExercises[exerciseName];
});
}
function loadAndRenderExercise(nextUserExercise) {
setUserExercise(nextUserExercise);
exerciseName = userExercise.exerciseModel.name;
function finishRender() {
// Get all problems of this exercise type...
var problems = exercises.filter(function() {
return $.data(this, "rootName") === exerciseName;
}).children(".problems").children();
// ...and create a new problem bag with problems of our new exercise type.
problemBag = makeProblemBag(problems, 10);
// Update related videos
Khan.relatedVideos.setVideos(userExercise.exerciseModel);
// Make scratchpad persistent per-user
if (user) {
var lastScratchpad = window.localStorage["scratchpad:" + user];
if (typeof lastScratchpad !== "undefined" && JSON.parse(lastScratchpad)) {
Khan.scratchpad.show();
}
}
// Generate a new problem
makeProblem();
}
if (isExerciseLoaded(exerciseName)) {
finishRender();
} else {
startLoadingExercise(exerciseName);
$(Khan)
.unbind("exerciseLoaded:" + exerciseName)
.bind("exerciseLoaded:" + exerciseName, function() {
finishRender();
});
}
}
function makeProblem(id, seed) {
// Enable scratchpad (unless the exercise explicitly disables it later)
Khan.scratchpad.enable();
// Allow passing in a random seed
if (typeof seed !== "undefined") {
problemSeed = seed;
// In either of these testing situations,
} else if ((testMode && Khan.query.test != null) || user == null) {
problemSeed = randomSeed;
}
// Set randomSeed to what problemSeed is (save problemSeed for recall later)
randomSeed = problemSeed;
// Check to see if we want to test a specific problem
if (testMode) {
id = typeof id !== "undefined" ? id : Khan.query.problem;
}
if (typeof id !== "undefined") {
var problems = exercises.children(".problems").children();
problem = /^\d+$/.test(id) ?
// Access a problem by number
problems.eq(parseFloat(id)) :
// Or by its ID
problems.filter("#" + id);
// Otherwise we grab a problem at random from the bag of problems
// we made earlier to ensure that every problem gets shown the
// appropriate number of times
} else if (problemBag.length > 0) {
problem = problemBag[problemBagIndex];
id = problem.data("id");
// No valid problem was found, bail out
} else {
return;
}
problemID = id;
// Find which exercise this problem is from
exercise = problem.parents("div.exercise").eq(0);
// Work with a clone to avoid modifying the original
problem = problem.clone();