Test existence of JSON value in JavaScript Array

Question

I have an array of JSON objects like so:

var myArray = [
  {name:'foo',number:2},
  {name:'bar',number:9},
  {etc.}
]

How do I detect if myArray contains an object with name="foo"?

Solution 1

Unless I'm missing something, you should use each at the very least for readability instead of map. And for performance, you should break the each once you've found what you're looking for, no reason to keep looping:

var hasFoo = false;
$.each(myArray, function(i,obj) {
  if (obj.name === 'foo') { hasFoo = true; return false;}
});  

Solution 2

With this:

$.each(myArray, function(i, obj){
   if(obj.name =='foo')
     alert("Index "+i + " has foo");
});

Cheers

Solution 3

for(var i = 0; i < myArray.length; i++) { 
   if (myArray[i].name == 'foo') 
        alert('success!') 
 }

Comments

[Quentin]

Those are not JSON objects

[James Montagne]

curious, why map instead of each?

[Felix Kling]

Don't use for...in to loop over an array.

[Felix Kling]

Array.prototype.each does not exists. Either you mean $.each from jQuery or Array.prototype.forEach which is only supported by newer browsers.

[mVChr]

I just happened to be messing around with the new jQuery 1.6 map on objects and so this was the first thing that came to mind. Can't imagine there's a performance difference, just need to get over the sorrow of return values being lost to the ether.

[James Montagne]

won't somebody think of the poor orphans!

[Felix Kling]

The disadvantage is that you can not terminate the looping earlier (as opposed to each).