var myWidth = 20;
var myHeight = 30;
allDims = [
{w: 20, h: 30},
{w: 10, h: 15}
]
if ($.inArray({w: myWidth, h: myHeight}, allDims) !== -1) {
...
}
Why is the if-condition always returning -1?
-
4It's always -1 because one object is never equal to another object, even if they contain the same data. The only exception to that rule is when the object stored in the array is stored by reference, and the object you're testing with is also a reference to that same object. In that case, they literally are the same object.user400654– user4006542013-06-24 14:15:02 +00:00Commented Jun 24, 2013 at 14:15
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1 Answer
This doesn't work because the equality test on objects is based on the equality of references.
From the MDN :
Two distinct objects are never equal for either strictly or abstract comparisons
So you must implement the index search yourself, by looping and comparing both w and h.
For example :
var index = -1;
for (var i=0; i<allDims.length; i++) {
if (allDims[i].w==myWidth && allDims[i].h==myHeight) {
index = i;
break;
}
}
If you want something more elegant, you could use filter and pass a function, but it would iterate over the whole array even when not needed. A generic function similar to indexOf but taking a callback to check equality can be designed :
Array.prototype.indexFunc = function(o, equal) {
for (var i=0; i<this.length; i++) {
if (equal(o,this[i])) return i;
}
return -1;
}
console.log(allDims.indexFunc({w:10, h:15}, function(a,b) {
return a.w==b.w && a.h==b.h
})); // logs 1
1 Comment
Alnitak
this answer does not deserve downvotes, it is 100% correct. The other (current) answer does not deserve upvotes - it is 100% incorrect.