Question

I want to do sth like this (c++):

const int SIZE = 5;
int array[SIZE];

but in JS. I’m using the SIZE value many times (for many arrays and later in the code) and I don’t want to put many literals with the same value (in case I have to edit it later). I read somewhere that there’s a const keyword in JS but it doesn’t work in every browser (not sure if that’s true but I want a universal solution). And the shorter/simpler the better! 😉

Answer 1

The const keyword is in fact non-standard, and only implemented by Mozilla therefore not guaranteed to work cross-browser (but apparently some browsers implement it, see the link on Bergi’s answer). Just use a regular variable, and the uppercase name to indicate it’s supposed to be a constant:

var SIZE = 5;
var arr = new Array(SIZE);

Note: if you pass anything other than a number to the Array constructor, it will create an array with length and the value you passed at index 0. In that case, it’s best to just use the literal notation (var arr = ['foo']). Also keep in mind that when you pass a number to the constructor, you’re just setting the initial length, and it’s always possible to add or remove elements after that.