Difference between Arrow and Normal functions.

Arrow function

• The arrow functions are work same as with normal functions. It was introduce in ES6.
• Syntax const variable = () => {}

• Ex
  var foo = _ => 'Hii';

• It's same as
  function name(params) {
  return 'Hii';
  }

• These arrow functions are make eassy our work and readablity.

• Normal function

  • var foo = function(name) { return function(age) { return function(city) { return ${name} ${age} ${city} } }

  }

• Arrow function

  • var foo = (name) => (age) => (city) => ${name} ${age} ${city};

Difference between normal and arrow functions.

    var name = "Mike";
    var obj = {
        name: "Tom",
        foo: function() {
            console.log(this);
            var bar1 = function() {
                console.log(this.name); // Point to Window(Parent)
            }
            var bar2 = () => {
                console.log(this.name); // Point to current Object
            }
            bar1();
            bar2();
        }
    }
    obj.foo();
    // If we not use var it point to parent
    var bar = () => {
        var x= "sad";
        let y= "sasa";
        console.log(this.x); // Window // undefined
        console.log(this.y); // sasa
    }
    bar();

Why we need Arrow function.

• Arrow functions cannot called with Constructer.
• Arrow functions are not having their own this. So, we cannot update using this.
  • Whenever we use this inside the arrow function it will check parent, until not find parent.
  • Arrow alway have lasical scope.

When use it.

• Use arrow function only when you have to use parent's this.
• Use only when we need it, according to requirenment.

Not use.

• It has not thier own this so we can not call it as a Constructor