JS Object-Oriented Learning Note VII (function and basic control structure)

"Function section"

1. Function built-in parameter array object arguments

function sum () {    var len = arguments.length;     var s = 0;     for (var i = 0;i<len;i++) {         s + = Arguments[i];    }     return s;}; var b = sum (1,2,3,4,5); alert (b); 15

2. Pre-defined built-in functions

parseint ()                 //String-to-integer type   The second parameter selects  the binary parseint (0777,8);p arsefloat ()/               /string to float type isNaN ()                    //To determine if it is not a number Not return Trueisfinite ()                 //Detect a non-Nan number that is not infinite or infinitesimal  returns Trueencodeuri ()                //url encoding available partial escape only escape parameter decodeURI ()                // URL decoding encodeuricomponent ()       //url encoding is not fully escaped all symbols are escaped decodeuricomponent ()       //url decoding eval ()                     //Parameters as JavaScript code performs slow performance unsafe alert ()                    //pop-up warning box  will block thread

3. variable extension type----function

var sum = function (A, b) {return a+b;}; var add = sum; Add (+); 3

4. function as parameter

function Add (a) {    return a+1;   }  function Addachd (a,b,func) {    return a+b+func (b);}  The function is passed as a parameter alert (ADDACHD (4,5,add)); 15//We can also use the function alert (Addachd (4,5,function (c) {return c+1;}) that can be reduced by a global declaration; 15

5. Self-tuning function

  The first parenthesis is the anonymous function itself  //The first parenthesis is placed inside the parameters of the anonymous function and immediately called  (function (a) {     alert (a+1);  }) (5);

6. Closures

In essence, the function B inside a function A does not use the variable a var B, which is internal to a. function A () {    var a = 9;    B = function () {        return A;    }    return B;     } Alert (B ());/*===================================================*/var result=[];  function foo () {      var i= 0;         for (; i<3;i=i+1) {            result[i]=function () {                alert (i);}}}    ; foo ();   Result[0] (); Closures are not assigned at the initial time and will be searched for corresponding values when executed result[1] ();  RESULT[2] ();  

7. Private Functions

/*===================================================*/function A () {    var a = 9;    B = function () {        alert (a);    }} alert (A ());//Any function has a default return value undefined function a () {    var a = 9;    var B = function () {        alert (a);       All child functions can call any variable declared by the parent function global function can not be closed packet can    }    B ();} A (); 9

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"Basic Control Structure"

"If/else" if (...) {    //code here ...} else{    //code here ...} "Switch/case" var a = 1; Switch (a) {case    1:      //code      ... break;    Case 2:      //code      ... break;    ...    Default:      //code      here ... Break } "while"  var i = 1, while (i<10) {    i++;} "Do." While "  var i = 1; do{   i++;} while (i<10) ' for ' for (var i = 0; i<10; i++) {     //code ...} "For...in" (typically used for array traversal) var arr = [1,2,3,4,5]; for (Var j in arr) {    //code    ... Alert (j+ "value:" +arr[j]);}

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JS Object-Oriented Learning Note VII (function and basic control structure)