Question

How to use constants in JavaScript

Answer 1

const a = 12;
console.log(a);

{
    const a = 100;
    console.log(a);
}

console.log(a);

// a = 800; // TypeError: invalid assignment to const 'a'

const arr = ['javascript', 'c', 'c++', "python"];
console.log(arr);

arr[4] = 'java';
console.log(arr);

arr[1] = 'AAA';
console.log(arr);

let arr2 = ['www', 'ccc', 'ddd'];

arr2 = arr;

// arr = arr2; // TypeError: invalid assignment to const 'arr'


// must initialized
// const b; // SyntaxError: missing = in const declaration




/*
run:

12
100
12
["javascript", "c", "c++", "python"]
["javascript", "c", "c++", "python", "java"]
["javascript", "AAA", "c++", "python", "java"]

*/

 

70+ SQL courses for beginners and professionals