JavaScript | Function Invocation
JavaScript Function Invocation is used to executes the function code and it is common to use the term “call a function” instead of “invoke a function”. The code inside a function is executed when the function is invoked.
Syntax:
- Invoking a Function as a Function:
function myFunction( var ) { return var; } myFunction( value ); - Invoking a Function as a Method:
var myObject = { var : value, functionName: function () { return this.var; } } myObject.functionName();
Parameters: It contains two parameters as mentioned above and described below:
- functionName: The functionName method is a function and this function belongs to the object and myObject is the owner of the function.
- this: The parameter this is the object that owns the JavaScript code and in this case the value of this is myObject.
Example 1: This example use function invocation to add two numbers.
<!DOCTYPE html><html> <head> <title> JavaScript Function Invocation </title></head> <body style="text-align:center;"> <h2>GeeksForGeeks</h2> <p> Function returns the addition of 50 and 60 </p> <p id="geeks"></p> <!-- Script to add two numbers --> <script> function myFunction(a, b) { return a + b; } document.getElementById("geeks").innerHTML = window.myFunction(50, 60); </script></body> </html> |
Output:
Example 2: This example use function invocation to concatenate strings.
<!DOCTYPE html><html> <head> <title> JavaScript Function Invocation </title></head> <body style="text-align:center;"> <h2>GeeksForGeeks</h2> <p> myObject.fullName() will return GeeksforGeeks </p> <p id="geeks"></p> <!-- Script to implement Function Invocation --> <script> var myObject = { firstName:"Geeks", middleName:"for", lastName: "Geeks", fullName: function() { return this.firstName + this.middleName + this.lastName; } } document.getElementById("geeks").innerHTML = myObject.fullName(); </script></body> </html> |
Output:
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