what is constant in javascript code example

Example 1: what is const in javascript

const age; // errror as const cannot be kept un-initialized;
const age = 20 ; 
const age = 21 , // error as once declared const variable cann't be
// re-declared in same scope or different scope.

Example 2: js define constant by element id

const elem = document.getElementById('elementID');

Example 3: constants in js

static methodName() { ... }
static propertyName [= value];

Example 4: how to create a constant in javascript

const example1 = "hello this is string variable" ; //this is string constant
const example2 = 12345 ; //this is numeric constant
const example3 = true ; //boolean constant