ECMA script is also know as JavaScript 6(ES6).
JavaScript ECMA Script 6 is introduce some of new features. Such as-
*JavaScript let
*JavaScript Const
*Array.find()
*Array.findIndex()
*Exponentiation
*Default parameter values

The let statement allow you to declare a variable with block scope and this of you can change dynamically. For example
Const arr=[“ram”,”shyam”,”lakshaman”];
for(let i=0;i<arr.length;i++){
console.log(arr[i]);
}

The Const statement allow you to declare a constant variable with a constant value.
Constant.
Constant variable are similar to let variable but constant variable value can’t be changed.