Constants

Const keyword is used to declare constant variables. Immutable is the one whose value cannot be modified. Const is the one whom we can assign value only once.

/**
 * to demonstrate the const variables, const variable are immutable
 */
const PRIMARY_VALUE = 100;
//PRIMARY_VALUE=200; second time assignment not allowed
console.log("PRIMARY_VALUE:::"+PRIMARY_VALUE);

const NUM_ARRAY = [1,2,3,4,5,6,7,8,9];
NUM_ARRAY.push(10);
//NUM_ARRAY = [11,12,13,14,15];//since array is const, reinitialization is not allowed. it will throw error
console.log("NUM_ARRY::"+NUM_ARRAY);

Output