What is the most concise and efficient way to find out if a JavaScript array contains a value?
This is the only way I know to do it:
function contains(a, obj) {
for (var i = 0; i < a.length; i++) {
if (a[i] === obj) {
return true;
}
}
return false;
}
Is there a better and more concise way to accomplish this?
This is very closely related to Stack Overflow question Best way to find an item in a JavaScript Array? which addresses finding objects in an array using indexOf.
Best Answer
Modern browsers have
Array#includes, which does exactly that and is widely supported by everyone except IE:You can also use
Array#indexOf, which is less direct, but doesn't require polyfills for outdated browsers.Many frameworks also offer similar methods:
$.inArray(value, array, [fromIndex])_.contains(array, value)(also aliased as_.includeand_.includes)dojo.indexOf(array, value, [fromIndex, findLast])array.indexOf(value)array.indexOf(value)findValue(array, value)array.indexOf(value)Ext.Array.contains(array, value)_.includes(array, value, [from])(is_.containsprior 4.0.0)R.includes(value, array)Notice that some frameworks implement this as a function, while others add the function to the array prototype.