jquery - How to create static array in JavaScript

Question

I am trying to create a static array. But I found that it can increase the item in the array at run time. How I can achieve static array in JavaScript? Why array is mutable in JavaScript?

var a = [];
//var a = new Array(3);
for (var i = 0; i < 5; i++) {
  //a.push(i);
  a[i] = i;
}

document.write(a);

Answer 1

You can freeze the array with Object.freeze:

"use strict";
var a = Object.freeze([0, 1, 2]);
console.log(a);
try {
  a.push(3);     // Error
} catch (e) {
  console.error(e);
}
try {
  a[0] = "zero"; // Error
} catch (e) {
  console.error(e);
}
console.log(a);