Iterate through associative array using sequential for loop

Question

I have a lot of data stored in associative array.

array = {'key':'value'};

How to loop throught an array like this using an normal for loop and not a loop like here: http://jsfiddle.net/HzLhe/

I don't want to use for-in because of this problems: Mootools when using For(...in Array) problem

It is messing with Mototools! http://stackoverflow.com/questions/7034837/mootools-when-using-for-in-array-problem — Jacob, Apr 04 '13 at 11:06
@Jacob that is because you have to use the `.hasOwnProperty` method to filter out the prototype chains properties — Jeff Shaver, Apr 04 '13 at 11:09
@Jacob You are using object and not array. These elements are different in JavaScript. `for .. in` loop is the best to iterate objects. — VisioN, Apr 04 '13 at 11:09
I know it is the best but I have to use a different way. Is it possible? — Jacob, Apr 04 '13 at 11:11
@Jacob You said you don't want to use it because there is a mootools problem. The mootools problem is only for arrays (which you should never iterate with for..in to begin with), not for plain objects. — Esailija, Apr 04 '13 at 11:17

Jeff Shaver · Accepted Answer · 2013-04-04T11:17:49.287

As others have pointed out, this isn't an array. This is a JavaScript object. To iterate over it, you will have to use the for...in loop. But to filter out the other properties, youw ill have to use hasOwnProperty.

Example:

var obj={'key1': 'value1','key2':'value2'};

for (var index in obj) {
    if (!obj.hasOwnProperty(index)) {
        continue;
    }
    console.log(index);
    console.log(obj[index]);
}

http://jsfiddle.net/jeffshaver/HzLhe/3/

score 4 · Answer 2 · answered Apr 04 '13 at 11:12

JavaScript does not have the concept of associative arrays. Instead you simply have an object with enumerable properties, so use a for..in loop to iterate through them. As stated above you may also want to perform a check with hasOwnProperty to ensure that you're not performing operations on inherited properties.

for (var prop in obj){
    if (obj.hasOwnProperty(prop)){
        console.log(obj[prop]);
    }
}

Iterate through associative array using sequential for loop

2 Answers2

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