eval()

• eval() is a built-in JavaScript function that takes a string and executes it as JavaScript code.

console.log(eval("2 + 3"));

eval("let x = 10;");

• Because eval() can access and modify variables in the current scope, the engine often has to disable many optimizations.
• Variables declared inside eval() do not leak into the surrounding scope in strict mode.

"use strict";

function test() {
    let x = 10;

    eval("let y = 20;");
    console.log(typeof y);
}

test();