Created at 280 days ago

Lexical scope

The lexical scope is the scope of a variable or function based on where it is defined in the source code. The scope is determined by the placement of variables and functions in the code, and it remains the same throughout the execution of the program.

const a = 2

function foo() {
  console.log(a)
}

function bar() {
  const a = 3

  foo()
}

foo() // 2
bar() // 2

Lexical scope isn't like this value, this value can be changed in the runtime.

var a = 2

function foo() {
  console.log(this.a)
}

function bar() {
  var a = 3

  foo.call({ a })
}

foo() // 2
bar() // 3