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underscore-basics.js
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underscore-basics.js
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// fetch our hero json file...
$.get('../../data/all.json', function(heroes) {
// === modify each record:
// add a property called hasHeight to each object that marks whether it
// has a height set or not
_.each(heroes, function(hero) {
if (hero.Height_cm !== "NA" ||
hero.Height_ft !== "NA") {
hero.hasHeight = true;
// convert to number from a string
hero.Height_cm = +hero.Height_cm;
} else {
hero.hasHeight = false;
}
});
// === find subset of original records
// find all the heroes that have a height
var heroes_with_height = _.filter(heroes, function(hero) {
return hero.hasHeight;
});
// === get a new array based on existing collection
// find all the heights
var heights = _.pluck(heroes_with_height, "Height_cm");
// === compute a single value
// compute the mean height
_.mixin({
sum : function(obj, key) {
var arr;
key = key || 'value';
if (_.isArray(obj) && typeof obj[0] === 'number') {
arr = obj;
} else {
arr = _(obj).pluck(key);
}
var val = 0;
for (var i=0, len = arr.length; i<len; i++) {
val += arr[i];
}
return val;
},
mean : function(obj, key) {
return _.sum(obj, key) / _(obj).size();
}
});
console.log("Mean height of all heroes", _.mean(heights));
console.log("Heroes with length", heroes_with_height);
});