Added LinkedList.every() with tests and docs.

DSA-a-day · Jan 29, 2014 · 96179fe · 96179fe
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diff --git a/docs/LinkedList.md b/docs/LinkedList.md
@@ -6,6 +6,7 @@ _Source: [./lib/LinkedList.js](../lib/LinkedList.js)_
 
 - <a name="toc_linkedlistarray"></a>[LinkedList](#linkedlistarray)
 - <a name="toc_linkedlistprototypeconcatlist1-listn"></a><a name="toc_linkedlistprototype"></a>[LinkedList.prototype.concat](#linkedlistprototypeconcatlist1-listn)
+- <a name="toc_linkedlistprototypeeverycallback-thisarg"></a>[LinkedList.prototype.every](#linkedlistprototypeeverycallback-thisarg)
 - <a name="toc_linkedlistprototypeforeachcallback-thisarg"></a>[LinkedList.prototype.forEach](#linkedlistprototypeforeachcallback-thisarg)
 - <a name="toc_linkedlistprototypegetindex"></a>[LinkedList.prototype.get](#linkedlistprototypegetindex)
 - <a name="toc_linkedlistprototypeindexofsearch-fromindex"></a>[LinkedList.prototype.indexOf](#linkedlistprototypeindexofsearch-fromindex)
@@ -48,13 +49,28 @@ _Source: [./lib/LinkedList.js](../lib/LinkedList.js)_
 
 <sub>Go: [TOC](#tableofcontents) | [LinkedList.prototype](#toc_linkedlistprototype)</sub>
 
+# LinkedList.prototype.every(callback, thisArg)
+
+> Determines whether each value in the [LinkedList](#linkedlistarray) passes a truth test.
+
+**Parameters:**
+
+- `{function} callback` The callback function to use as a truth test. Will be passed (value, index, [LinkedList](#linkedlistarray), [thisArg]). Should return true or false.
+- `{object} thisArg` Optional context to pass as `this`.
+
+**Return:**
+
+`{boolean}` Whether every value in the [LinkedList](#linkedlistarray) passed the truth test.
+
+<sub>Go: [TOC](#tableofcontents) | [LinkedList.prototype](#toc_linkedlistprototype)</sub>
+
 # LinkedList.prototype.forEach(callback, thisArg)
 
 > Executes a provided function once per node value.
 
 **Parameters:**
 
-- `{function} callback` The callback function to call for each node value. Will be passed (value, index, [LinkedList](#linkedlistarray), [thisArg])
+- `{function} callback` The callback function to call for each node value. Will be passed (value, index, [LinkedList](#linkedlistarray), [thisArg]).
 - `{object} thisArg` Optional context to pass as `this`.
 
 **Return:**

diff --git a/lib/LinkedList.js b/lib/LinkedList.js
@@ -55,14 +55,32 @@ var LinkedList = (function () {
     return this;
   };
 
-  //TODO LinkedList.prototype.every
+  /**
+   * Determines whether each value in the LinkedList passes a truth test.
+   *
+   * @param {function} callback The callback function to use as a truth test. Will be passed (value, index, LinkedList, [thisArg]). Should return true or false.
+   * @param {object} thisArg Optional context to pass as `this`.
+   * @return {boolean} Whether every value in the LinkedList passed the truth test.
+   */
+   LinkedList.prototype.every = function (callback, thisArg) {
+    // Iterate over each node and call callback for each node value
+    var current = this.head;
+    for (var i = 0; i < this.length; i++) {
+      if (!callback(current.value, i, this, thisArg)) {
+        return false;
+      }
+      current = current.next;
+    }
+
+    return true;
+   };
 
   //TODO LinkedList.prototype.filter
 
   /**
    * Executes a provided function once per node value.
    *
-   * @param {function} callback The callback function to call for each node value. Will be passed (value, index, LinkedList, [thisArg])
+   * @param {function} callback The callback function to call for each node value. Will be passed (value, index, LinkedList, [thisArg]).
    * @param {object} thisArg Optional context to pass as `this`.
    * @return {LinkedList} The LinkedList.
    */

diff --git a/test/LinkedListSpec.js b/test/LinkedListSpec.js
@@ -29,6 +29,29 @@ test("LinkedList.prototype.concat()", function (t) {
   t.end();
 });
 
+test("LinkedList.prototype.every()", function (t) {
+  var l = new LinkedList([ "foo", "bar", "baz" ]);
+  var res = l.every(function (val, idx, ll, context) {
+    var v, i;
+    switch (idx) {
+      case 0: v = "foo"; i = 0; break;
+      case 1: v = "bar"; i = 1; break;
+      case 2: v = "baz"; i = 2; break;
+    }
+    t.equal(val, v, "val should be equal to " + v);
+    t.equal(idx, i, "idx should be equal to " + i);
+    t.deepEqual(ll, l, "ll should be the same as l");
+    t.deepEqual(context, { "cat": "dog" }, "context should be the same");
+    return (val !== "bar");
+  }, { "cat": "dog" });
+  t.deepEqual(res, false, "every value must not be equal to bar");
+  res = l.every(function (val, idx, ll, context) {
+    return (val !== "boom");
+  });
+  t.deepEqual(res, true, "every value must not be equal to boom");
+  t.end();
+});
+
 test("LinkedList.prototype.forEach()", function (t) {
   var l = new LinkedList([ "foo", "bar", "baz" ]);
   var res = l.forEach(function (val, idx, ll, context) {