ES6: 20 Use class Syntax to Define a Constructor Function

ES6 provides a new syntax to help create objects, using the keyword class. This is to be noted, that the class syntax is just a syntax, and not a full-fledged class based implementation of object oriented paradigm, unlike in languages like Java, or Python, or Ruby etc. In ES5, we usually define a constructor function, and use the new keyword to instantiate an object.
var SpaceShuttle = function(targetPlanet){
this.targetPlanet = targetPlanet;
}
var zeus = new SpaceShuttle('Jupiter');
The class syntax simply replaces the constructor function creation:
class SpaceShuttle {
constructor(targetPlanet){
this.targetPlanet = targetPlanet;
}
}
const zeus = new SpaceShuttle('Jupiter');
Notice that the class keyword declares a new function, and a constructor was added, which would be invoked when new is called - to create a new object.
Use class keyword and write a proper constructor to create the Vegetable class. The Vegetable lets you create a vegetable object, with a property name, to be passed to constructor.
function makeClass() {
"use strict";
class Vegetable {
constructor (name){
this.name=name;
}
}
return Vegetable;
}
const Vegetable = makeClass();
const carrot = new Vegetable('carrot');
console.log(carrot.name); // => should be 'carrot'

Comments

Post a Comment

Popular posts from this blog

ES6 : 5 Prevent Object Mutation

As seen in the previous post declaration alone doesn't really protect your data from mutation. To ensure your data doesn't change, JavaScript provides a function Object.freeze() to prevent data mutation. Once the object is frozen, you can no longer add, update, or delete properties from it. Any attempt at changing the object will be rejected without an error. let obj = { name:"FreeCodeCamp" review:"Awesome" }; Object.freeze(obj); obj.review = "bad"; //will be ignored. Mutation not allowed obj.newProp = "Test"; // will be ignored. Mutation not allowed console.log(obj); // { name: "FreeCodeCamp", review:"Awesome"}
Read more

ES6: 1 Explore Differences Between the var and let Keywords

One of the biggest problems with declaring variables with the var keyword is that you can overwrite variable declarations without an error. var camper = 'James'; var camper = 'David'; console.log(camper); // logs 'David' As you can see in the code above, the camper variable is originally declared as James and then overridden to be David . In a small application, you might not run into this type of problem, but when your code becomes larger, you might accidentally overwrite a variable that you did not intend to overwrite. Because this behavior does not throw an error, searching and fixing bugs becomes more difficult. A new keyword called let was introduced in ES6 to solve this potential issue with the var keyword. If you were to replace var with let in the variable declarations of the code above, the result would be an error. let camper = 'James'; let camper = 'David'; // throws an error This error can be seen...
Read more

CSS Grid: Reduce Repetition Using the repeat Function

 When we used grid-template-columns and grid-template-rows to define the structure of a grid, you entered a value for each row or column you created. Lets say you want a grid with 100 rows of the same height. It isn't very practical to insert 100 values individually. Fortunately, there's a better way - by using the repeat function to specify the number of times you want your column or row to be repeated, followed by a comma and the value you want to repeat. Here's an example that would create the 100 row grid, each row at 50px tall. grid-template-rows: repeat(100, 50px); You can also repeat multiple values with the repeat function, and insert the function amongst other values when defining a grid structure. Here's what I mean: grid-template-columns: repeat(2, 1fr 50px) 20px;  this will be translated to :            grid-template-columns:1fr 50px 1fr 50px  20px;   1fr 50px is repeated t...
Read more