searching for a specific array member

[jimfog]

If I wanted to check if a an array contains a specific member....'car' for example.

What method should I use to do it? I looked at some methods in w3schools tutorial but I

cannot find a method that can perform a specific task.

 

The logic is that if a specific member is found in the array then do ...this.

[Ingolme]

Loop through the array until you find the value you're looking for. You can build a function that does it for you

function contains(arr, value) {    for(var i = 0; i < arr.length; i++) {        if(arr[i] == value) {             return true;        }    }    return false;}// Use the functionvar N = ["a", "b", "c"];if(contains(N, "c")) {    alert("c is in the array");}

[davej]

I think most of us programmers would use the obvious approach that foxy mentions above, but I guess you can also use indexOf() since it seems to work on an array as well as on a string...

 

http://www.w3schools.com/jsref/jsref_indexof_array.asp

[Ingolme]

I wasn't aware indexOf was also an array method. I can't remember a case in Javascript when I needed to know if an array contained something.

 

I can see why I never learnt it, though:

The indexOf() method is not supported in Internet Explorer 8 and earlier.

 

[jimfog]

the index of method has a drawback. It returns the index of the member-if that is found of course.

So, you have to know from before the possible index of the member you are looking.

 

That index may vary. I would go the function that is depicted above since I only want a true/false and nothing else.

It suits my needs better.

[davej]

I use indexOf() with strings quite often. If the search string isn't found then the function returns -1, which is easy to test for -- but a loop is a better choice for arrays because of IE8.

[thescientist]

the index of method has a drawback. It returns the index of the member-if that is found of course.So, you have to know from before the possible index of the member you are looking. That index may vary. I would go the function that is depicted above since I only want a true/false and nothing else.It suits my needs better.

I'm not sure why you think you need to know the index to use indexOf just like the contains function, since for your requirement you only care if it's in the function or not. From the docs

This method returns -1 if the value to search for never occurs.[/size]

var N = ["a", "b", "c"];if(N.indexOf("c") >= 0) {  alert("c is in the array");}

So, really, it just comes down to whether or not you need to support IE8, or you could use a library to normalize browser differences of the implementation

http://api.jquery.com/jQuery.inArray/

http://lodash.com/docs#indexOf

Edited October 30, 2013 by thescientist

[jimfog]

I used the in array method after all.Is there any drawback in using it instead of the function above?

I am searching for the best alternative here.

[thescientist]

not having to maintain it on your own, since you're already using jQuery and they have a much better capacity for regression and unit testing.

[jimfog]