How can I check if a value is present in an array in javascript?

Question

I have the following in javascript:

 var colors = ["dark", "light"]; if (localStorage.themeColor) { 

How can I modify this to not only check that localStorage.themeColor is set but also to check that it is one of the two values in the array?

Answer 1

You can use indexOf in conjunction with your existing check for themeColor:

if(localStorage.themeColor && colors.indexOf(localStorage.themeColor) > -1) { // Do stuff } 

Answer 2

You can say something like:

var colors = ["dark", "light"]; if (localStorage.themeColor && colors.indexOf(localStorage.themeColor) != -1) { 

For indexOf see:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf?redirectlocale=en-US&redirectslug=JavaScript%2FReference%2FGlobal_Objects%2FArray%2FindexOf

Answer 3

 for(var i=0;i<colors.length;i++) { if(localStorage.themeColor==colors[i]) { alert(colors[i]); } else{ alert("colors not set"); } 

Answer 4

colors.indexOf("dark") !== -1

indexOf returns -1 if the argument passed does not exist in colors

Answer 5

You can solve it like this

var colors = ["dark", "light"]; if (localStorage.themeColor && colors.indexOf(localStorage.themeColor) > -1) { // Your Code... } 

I tested it in the case of localStorage.themeColor == light and localStorage.themeColor is undefined

Answer 6

you should create a prototype like this

Array.prototype.contains = function(elem) { for (var i in this) { if (this[i] == elem) return true; } return false; } 

And your array here

var colors = ["dark", "light"]; 

Finally call the function using colors.contains("dark") // this will return true