jQuery.inArray(), how to use it right?

jQuery.inArray(), how to use it right?

First time I work with jQuery.inArray() and it acts kinda strange.
If the object is in the array, it will return 0, but 0 is false in Javascript. So the following will output: “is NOT in array”
var myarray = [];

if(jQuery.inArray(“test”, myarray)) {
console.log(“is in array”);
} else {
console.log(“is NOT in array”);

I will have to change the if statement to:
if(jQuery.inArray(“test”, myarray)==0)

But this makes the code unreadable. Especially for someone who doesn’t know this function. They will expect that jQuery.inArray(“test”, myarray) gives true when “test” is in the array.
So my question is, why is it done this way? I realy dislike this. But there must be a good reason to do it like that.


Solution 1:

inArray returns the index of the element in the array, not a boolean indicating if the item exists in the array. If the element was not found, -1 will be returned.

So, to check if an item is in the array, use:

if(jQuery.inArray("test", myarray) !== -1)

Solution 2:

$.inArray returns the index of the element if found or -1 if it isn’t — not a boolean value. So the correct is

if(jQuery.inArray("test", myarray) != -1) {
    console.log("is in array");
} else {
    console.log("is NOT in array");

Solution 3:

The answer comes from the first paragraph of the documentation check if the results is greater than -1, not if it’s true or false.

The $.inArray() method is similar to JavaScript’s native .indexOf() method in that it returns -1 when it doesn’t find a match. If the first element within the array matches value, $.inArray() returns 0.

Because JavaScript treats 0 as loosely equal to false (i.e. 0 == false, but 0 !== false), if we’re checking for the presence of value within array, we need to check if it’s not equal to (or greater than) -1.

Solution 4:

The right way of using inArray(x, arr) is not using it at all, and using instead arr.indexOf(x).

The official standard name is also more clear on the fact that the returned value is an index thus if the element passed is the first one you will get back a 0 (that is falsy in Javascript).

(Note that arr.indexOf(x) is not supported in Internet Explorer until IE9, so if you need to support IE8 and earlier, this will not work, and the jQuery function is a better alternative.)

Solution 5:

Or if you want to get a bit fancy you can use the bitwise not (~) and logical not(!) operators to convert the result of the inArray function to a boolean value.

if(!!~jQuery.inArray("test", myarray)) {
    console.log("is in array");
} else {
    console.log("is NOT in array");

Solution 6:

I usually use

if(!(jQuery.inArray("test", myarray) < 0))


if(jQuery.inArray("test", myarray) >= 0)