I needed a bit of JavaScript that would look at an array of objects and see if it contained an element that matched a certain criteria.  I’m sure that this is online somewhere, but I couldn’t turn it up.  There are lots of examples for finding if an array contains a certain specific element, but that wasn’t what I needed.  In my case I wanted to pick out the object from an array that had ‘type’ property equal to a certain string. 

Since I find so many great examples online I wanted to give somthing back to the community in the hope that this will save someone time and effort down the line. 

I’m a long time out from my last formal class in programming languages so if this type of search has a particular name, please let me know!

 

<script language="JavaScript">

/* search all elements in an array for one that has a property key equal to value */
Array.prototype.deepContains = function (key,value) {
var i = this.length;
var compareFunc = function(x) { return x[key] == value; };
while (i--) {
if (compareFunc (this[i])) {
return true;
}
}
return false;
}
/* build an array for testing */
var arr = new Array();
var obj = new Object(); obj['id'] = 22; arr[0] = obj;
obj = new Object(); obj['id'] = 54; arr[1] = obj;
obj = new Object(); obj['id'] = 77; arr[2] = obj;
/* usage example */
alert (arr.deepContains( 'id', 1 ) );  // false, no Object has 'id' = 1
alert (arr.deepContains( 'id', 54 ) );  // Object with 'id' = 54
</script>