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',
    },

Answer 1

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/