What are 2 ways to call a javascript function?
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All Functions are MethodsIn JavaScript all functions are object methods. If a function is not a method of a JavaScript object, it is a function of the global object (see previous chapter). The example below creates an object with 3 properties, firstName, lastName, fullName. Example const person = { // This will return "John Doe": Try it Yourself » In the example above, this.firstName means the firstName property of this. Same as: this.firstName means the firstName property of person. What is this?In JavaScript, the Which object depends on how The
The JavaScript call() MethodThe It can be used to invoke (call) a method with an owner object as an argument (parameter). With This example calls the fullName method of person, using it on person1: Example const person = { // This will return "John Doe": Try it Yourself » This example calls the fullName method of person, using it on person2: Example const person = { //
This will return "Mary Doe" Try it Yourself » The call() Method with ArgumentsThe Example const person = { const person1 = { person.fullName.call(person1, "Oslo", "Norway"); Try it Yourself » The code inside a JavaScript Invoking a JavaScript FunctionThe code inside a function is not executed when the function is defined. The code inside a function is executed when the function is invoked. It is common to use the term "call a function" instead of "invoke a function". It is also common to say "call upon a function", "start a function", or "execute a function". In this tutorial, we will use invoke, because a JavaScript function can be invoked without being called. Invoking a Function as a FunctionExample function myFunction(a, b) { Try it Yourself » The function above does not belong to any object. But in JavaScript there is always a default global object. In HTML the default global object is the HTML page itself, so the function above "belongs" to the HTML page. In a browser the page object is the browser window. The function above automatically becomes a window function. NoteThis is
a common way to invoke a JavaScript function, but not a very good practice. myFunction() and window.myFunction() is the same function: Example function myFunction(a, b) { Try it Yourself » What is this?In JavaScript, the Which object depends on how The
The Global ObjectWhen a function is called without an owner object, the value of In a web browser the global object is the browser window. This example returns the window object as the value of Examplelet x = myFunction(); // x will be the window object function myFunction() { Try it Yourself » Invoking a function as a global function, causes the value of this to be the global object. Invoking a Function as a MethodIn JavaScript you can define functions as object methods. The following example creates an object (myObject), with two properties (firstName and lastName), and a method (fullName): Example const myObject = { Try it Yourself » The fullName method is a function. The function belongs to the object. myObject is the owner of the function. The thing called Test it! Change the fullName method to return the value of
Example const myObject = { // This will return [object Object] (the owner object) Try it Yourself » Invoking a function as an object method, causes the
value of Invoking a Function with a Function ConstructorIf a function invocation is preceded with the It looks like you create a new function, but since JavaScript functions are objects you actually create a new object: Example // This is a function constructor: // This creates a new object // This will return "John" Try it Yourself » A constructor invocation creates a new object. The new object inherits the properties and methods from its constructor. The How do you call a function JavaScript?The call() method is a predefined JavaScript method. It can be used to invoke (call) a method with an owner object as an argument (parameter). With call() , an object can use a method belonging to another object.
What are the two ways to call a function?But for functions with arguments, we can call a function in two different ways, based on how we specify the arguments, and these two ways are: Call by Value. Call by Reference.
What are the two types of functions in JS?Functions in JavaScript are very similar to those of some other scripting high-level languages such as TypeScript and there are two types of functions: predefined and user-defined.
How many ways can you call a function in JavaScript?In JavaScript there are four ways through which you can call a function and perform the action.
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