How to loop through items in a js object?

Question

how can I loop through these items?

var userCache = {};
userCache['john']     = {ID: 234, name: 'john', ... };
userCache['mary']     = {ID: 567, name: 'mary', ... };
userCache['douglas']  = {ID: 42,  name: 'douglas', ... };

the length property doesn't work?

userCache.length

Answer 1

You can loop over the properties (john, mary and douglas) of your userCache object as follows:

for (var prop in userCache) {
    if (userCache.hasOwnProperty(prop)) {
        // You will get each key of the object in "prop".
        // Therefore to access your items you should be using:
        //     userCache[prop].name;
        //     userCache[prop].ID;
        //     ...
    }
}

It is important to use the hasOwnProperty() method, to determine whether the object has the specified property as a direct property, and not inherited from the object's prototype chain.

Answer 2

for(var i in userCache){
   alert(i+'='+userCache[i]);
}

Answer 3

For this you would use a for.. in loop

for (var prop in userCache) {
    if (userCache.hasOwnProperty(prop)) {
        alert("userCache has property " + prop + " with value " + userCache[prop]);
    }
}

The `.hasOwnProperty is needed to avoid members inherited through the prototype chain.

Answer 4

there's no length property because you're not using an indexed array.

see here for iterating over the properties.

http://stackoverflow.com/questions/1200562/difference-in-json-objects-using-javascript-jquery/1200713#1200713