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The Difference Between Statements and Expressions in Javascript

Javascript This

A lot of people find this keyword in Javascript very confusing. Depending on where is it used and defined it can have different value.

function simpleFunction () {
  console.log(this === window); 
  //prints true to console
}

function withStrict () {
  'use strict';
  console.log(this);
  // prints undefined to console
}

function Person() {
    this.name = "Maksim"

    this.logName = function(){
        console.log(this.name)
    }
}

const person = new Person();
person.logName() // Will output `Maksim`

const user = {
    name: 'Maksim',
    logName: function(){
        console.log(this.name)
        // will log `Maksim`
    }
}

const user = {
    name: 'Maksim',
    logName: function(){
        'use strict'
        console.log(this)
        console.log(this.name)
    }
}

const brokenLogName = user.logName
brokenLogName() // Will give `TypeError: this is undefined`

document.querySelector('#button').addEventListener('click', function(e) {
  console.log(this) //HTMLElement
}