![Define a functionfunction f(msg) {alert(msg);}// overridefunction f(msg1, msg2) {alert(msg1 + ' ' + msg2);}// arguments keywordfunction f() { for (var i = 0; i < arguments.length; i ++ ) { alert(arguments[i]);}}// callf();](https://image.slidesharecdn.com/js-function-111013013116-phpapp02/85/Javascript-Function-2-320.jpg)
![Built-in typesNumbervarnum = new Number(2); or varnum= 2; Objectvarobj = new Object(); or varobj = {}; Arrayvararr = new Array(1, 2, 3); or vararr = [1, 2, 3];Stringvarstr = new String('Hello'); or varstr = 'Hello';Regular expressionvar regex = new RegExp('\s*'); or varregex = /\s*/;etc... - w3schools.com/js](https://image.slidesharecdn.com/js-function-111013013116-phpapp02/85/Javascript-Function-5-320.jpg)
Javascript Function
- 2. Define a functionfunction f(msg) {alert(msg);}// overridefunction f(msg1, msg2) {alert(msg1 + ' ' + msg2);}// arguments keywordfunction f() { for (var i = 0; i < arguments.length; i ++ ) { alert(arguments[i]);}}// callf();
- 3. Define a classvarMyAlert = function (msg) { this.msg = msg;// define a methodthis.f = function () { alert('Hello ' + this.msg); };};varmyalert = new MyAlert('Mary');// call f methodmyalert.f();
- 4. Define a class by prototypevarMyAlert = function (msg) { this.msg = msg;};// use prototype to define a methodMyAlert.prototype.f = function () { alert(this.msg);};prototype definition uses less memory
- 5. Built-in typesNumbervarnum = new Number(2); or varnum= 2; Objectvarobj = new Object(); or varobj = {}; Arrayvararr = new Array(1, 2, 3); or vararr = [1, 2, 3];Stringvarstr = new String('Hello'); or varstr = 'Hello';Regular expressionvar regex = new RegExp('\s*'); or varregex = /\s*/;etc... - w3schools.com/js
- 6. String prototypeString.prototype.f = function () { alert(this);};varstr = 'Hello Mary';str.f();
- 7. Define a function (more)// goes to top of current scopefunction f(msg) { alert(msg);}// assignmentvarf = function (msg) { alert(msg);};// use new keywordvar f = new Function('msg', 'alert(msg);');
- 8. Function prototypeFunction.prototype.f= function () { alert(this.toString());};var f = function () { alert('This is a function.');};// does NOT alert "This is a function." f.f();
- 9. Anonymous function(function (msg) { alert('This is ' + msg);})('anonymous');(function (msg) {// this line does NOT get executed alert('This is ' + msg);}).f();
- 10. Callbackfunction f(callback) { callback();}function dosomething() { alert('This is a callback function.');}f(dosomething);
- 11. Return a functionfunction f() {varnum= 1;// num can be accessed in inner functionvarinnerf = function () {alert( 'inner function called, num: ' + num); }; return innerf;}// f2 now is a functionvarf2 = f();f2();
- 12. Closurefunction f() {varnum= 1;// num can be accessed in inner functionvarinnerf = function () {num ++; alert( 'inner function called, num: ' + num ); }; return innerf;}// f2 now is a functionvar f2 = f();f2();
- 13. SummaryFuntionis a objectused to create classcan be passed as parametercan be returnedcreates a closure when defined in another function