javascript function declaration vs arrow function
Regular functions created through function declarations / expressions are both constructible and callable. ... Arrow functions (and methods) are only callable i.e arrow functions can never be used as constructor functions. Hence, they can never be invoked with the new keyword.js arrow vs normal function
// jsdrops.com/arrow-functions
this.whoIsThis = 'TOP'; // Identify this scope
// 1) Defining
const fancyObj {
whoIsThis: 'FANCY', // Identify this object
regularF: function () {
console.log('regularF', this.whoIsThis);
},
arrowF: () => {
console.log('arrowF', this.whoIsThis);
},
};
// 2) Calling
console.log('TOP-LEVEL', this.whoIsThis); // It's "TOP" here
fancyObj.regularF(); // Output #1 (Fancy)
fancyObj.arrowF(); // Output #2 (Top)
fancyObj.regularF.call({whoIsThis: 'FAKE'}); // Output #3 (Fake)
fancyObj.arrowF.call({whoIsThis: 'FAKE'}); // Output #4 (Top)js arrow function vs function
// currently common pattern
var that = this;
getData(function(data) {
that.data = data;
});
// better alternative with arrow functions
getData(data => {
this.data = data;
});Copyright © 2021 Codeinu
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