Constants also are known as immutable variables are a special type of variables whose content is not changed. In Es6 a constant is defined using const keyword. Constants in Es6 enable protection to overwrite a variable value, improve performance and helps PROGRAMMERS to write readable and CLEANER CODE.

Example:

In Es6

const WEBSITE_URL = "http://www.abc.com";

WEBSITE_URL="new url"; // generate an error;

console.log (WEBSITE_URL);

In prior version of Es6

// and only in global CONTEXT and not in a block scope

Object.defineProperty(type of global === "object" ? global : window, "WEBSITE_URL", {

value: "http://www.abc.com", enumerable: TRUE,

writable: false,

configurable: false

});

console.log (WEBSITE_URL);

Constants also are known as immutable variables are a special type of variables whose content is not changed. In Es6 a constant is defined using const keyword. Constants in Es6 enable protection to overwrite a variable value, improve performance and helps programmers to write readable and cleaner code.

Example:

In Es6

const WEBSITE_URL = "http://www.abc.com";

WEBSITE_URL="new url"; // generate an error;

console.log (WEBSITE_URL);

In prior version of Es6

// and only in global context and not in a block scope

Object.defineProperty(type of global === "object" ? global : window, "WEBSITE_URL", {

value: "http://www.abc.com", enumerable: true,

writable: false,

configurable: false

});

console.log (WEBSITE_URL);