() => 'Hello world!!'
Functions in JavaScript
Ahmed Murtaza 😎
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Functions
in JavaScript
what are
Functions are:
are First class object
Declared with literals
Function as Data
Return values
Create Modules(scopes)
As Callbacks
Declared with literals
1 - function (keyword)
2 - name (optional)
3 - list of Parameters (optional)
4 - body
Example:
function print(message){
//body
console.log(message);
}
print("Hi, this is Ahmed Murtaza");
Functions as Data
Store in variables
Array entries
Object literals
Referenced by variables
//No recursion possible
let print = function(){
console.log('print me!!');
}
print();
//with recursion
let facto = function factorial( f ){
if( f <= 1) return 0;
return f * factorial(f-1)
}
facto(5);
Referenced by Array Entries
function print(msg){ return msg; }
let values = [facto];
values[0]('Web is awesome!!');
Stored in Object Literals
let human = {
age: 27,
walk: function(){ console.log('walking'); },
}
human.walk(); //walking
As Parameters
function upperCase(val){
return val.toUpperCase();
}
function smallCase(val){
return val.toLowerCase();
}
function decorate(a, passFunction){
console.log(passFunction(a));
}
decorate('Pakistan', capitalCase); //PAKISTAN
decorate('PAKISTAN',smallCase); //pakistan
Return Values
//Return
function returnMin(a, b){
return Math.min(a,b);
}
console.log(returnMin(2,7)); //2
//Does not Return
function printMin(a, b){
console.log(2,7);
}
printMin(2,7); //2
functions can and cannot return values
Create Scopes
//self invoking anonymous function
(function(){
let myVal = 'JavaScript Functions';
. . . //rest of your work
})();
console.log(myVal); //Reference error
Callbacks
function greeting(name){
alert('hello'+name);
}
function processUserInput(callback){
let name = prompt('please enter your name');
callback(name);
}
processUserInput(greeting);
Function passed as parameter to another function
Thank You
Functions in JavaScript
By Ahmed Murtaza
Functions in JavaScript
overview of Functions in javascript, functions as data, stored in variables, array entries, object literals, callbacks, scopes, hoisting
