As a good programming practice, we should write individual functions/methods for dealing with individual actions. And, writing only one method/function for all actions is a thing. However, sticking to good practice takes a toll on the readability and comprehensibility of the code, because defining a separate function for each action means that the output of a single function/method is input. This makes code comprehensibility even worse, as the function needs to be nested in reverse order. This is where method chaining comes to the rescue.
Method Chaining is a programming strategy that simplifies and embellishes your code. It is a mechanism of calling a method on another method of the same object.
JavaScript this keyword refers to the current object in which it is called. Thus, when a method returns this, it simply returns an instance of the object in which it is returned. Since the returned value is an instance of an object, it is, therefore, possible to call another method of an object to the returned value, which is its instance. And this makes method chaining possible in JavaScript.
Example 1: In this example, each method in Land.prototype returns this, which refers to the entire instance of that Land object. And this would help in calling a method on another method of the same object.
Javascript
//creating a function Land() function Land() { this.area = ''; this.status = 'for Sale'; } //Setting status open for sale Land.prototype.open = function() { this.status = 'Open for Sale'; return this; } //Setting status not for sale Land.prototype.close = function() { this.status = 'Not for Sale'; return this; } //Setting Parameters Land.prototype.setParams = function(area) { this.area = area; return this; } //printing land status Land.prototype.doorStatus = function() { console.log('The',this.area,'Land is',this.status); return this; } //creating a land object var land = new Land(); land.setParams("500 sq ft") .close() .doorStatus() .open() .doorStatus(); |
Output:
The 500 sq ft Land is Not for Sale VM1106:24 The 500 sq ft Land is Open for Sale
Example 2: In this example, we will chain the inbuilt methods of the String
Javascript
var firstName = " Rajat "; console.log(firstName); var modifiedName = firstName.toUpperCase() .trim(); console.log(modifiedName) |
Rajat RAJAT
