Check if JavaScript object contains X?

Question

I need to know if a JavaScript object contains a certain variable.

EG: Check if 'map' contains 'here'

var map = {
    '10': '0',
    '20': '0',
    '30': 'here',
    },

Derek 朕會功夫 · Accepted Answer · 2012-12-09 06:23:31Z

4

You have to loop through the object to test it:

var chk = false;
for(var key in map){
    if(map[key] == "here"){
        chk = true;
        break;
    }
}
alert(chk?"Yup":"Nah");

You can also put this in Object prototype:

Object.prototype.ifExist = function(txt){
    var chk = false;
    for(var key in this){
        if(this[key] == txt){
            chk = true;
            break;
        }
    }
    return chk;
}

//map.ifExist("here");
//return true

Demo: http://jsfiddle.net/DerekL/yWnYy/

edited Dec 9, 2012 at 6:23

answered Dec 9, 2012 at 6:01

Derek 朕會功夫

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Comments

Blender · Accepted Answer · 2012-12-09 06:02:22Z

1

You'll have to iterate over the object using the for..in syntax:

function in_object(value, object) {
    for (var key in map) {
        if (map[key] == value) {
            return true;
        }
    }

    return false;
}

Here's an example:

> in_object('heres', map)
false
> in_object('here', map)
true

answered Dec 9, 2012 at 6:02

Blender

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