Javascript foreach loop on associative array object

The Solution to Javascript foreach loop on associative array object is


The .length property only tracks properties with numeric indexes (keys). You're using strings for keys.

You can do this:

var arr_jq_TabContents = {}; // no need for an array

arr_jq_TabContents["Main"] = jq_TabContents_Main;
arr_jq_TabContents["Guide"] = jq_TabContents_Guide;
arr_jq_TabContents["Articles"] = jq_TabContents_Articles;
arr_jq_TabContents["Forum"] = jq_TabContents_Forum;

for (var key in arr_jq_TabContents) {
    console.log(arr_jq_TabContents[key]);
}

To be safe, it's a good idea in loops like that to make sure that none of the properties are unexpected results of inheritance:

for (var key in arr_jq_TabContents) {
  if (arr_jq_TabContents.hasOwnProperty(key))
    console.log(arr_jq_TabContents[key]);
}

edit — it's probably a good idea now to note that the Object.keys() function is available on modern browsers and in Node etc. That function returns the "own" keys of an object, as an array:

Object.keys(arr_jq_TabContents).forEach(function(key, index) {
  console.log(this[key]);
}, arr_jq_TabContents);

The callback function passed to .forEach() is called with each key and the key's index in the array returned by Object.keys(). It's also passed the array through which the function is iterating, but that array is not really useful to us; we need the original object. That can be accessed directly by name, but (in my opinion) it's a little nicer to pass it explicitly, which is done by passing a second argument to .forEach() — the original object — which will be bound as this inside the callback. (Just saw that this was noted in a comment below.)

~ Answered on 2013-09-14 17:42:52


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