First, the way the function is defined
(1) Normal way
Syntax: function name (parameter) {
function body
}
Code: |
Function method () { Alert ("TestMethod"); } Method (); |
(2) anonymous function
Syntax: function (parameter) {
function body
}
Code: |
var method = function () { Alert ("yyy"); }; Method (); |
(3) Object functions
Syntax: new function (argument list, function body);
Note: The parameter name must be in the form of a string, and the last one is the function body and the function body needs to be in string form.
Code: |
var fn = new Function ("A", "B", "Alert (a+b)"); FN (2,5); |
Second, the parameters of the function
Note: (1) parameter does not have VAR modifier
(2) The format of formal parameters and arguments is not necessarily equal
(3)arguments objects are arrays that encapsulate the passed arguments
Code: |
function fn (a,b,c) { var sum = a+b+c; alert (sum); Arguments is the number of arrays that encapsulate the passed arguments for (Var i=0;i<arguments.length;i++) { Alert (Arguments[i]); } } FN (1,2,4,8); |
Third, the return value of the function
(1) You do not have to indicate whether you have a return value when defining a function
(2) The return value simply passes the return keyword and the return code does not execute
Code: |
function fn (A, b) { return a+b; Alert ("XXXX");// The code here does not execute } Alert (FN (2,3)); |
Four, JS global function
Global properties and functions are available for all built-in JavaScript objects
(1) encoding and decoding
decodeURI () decodes a coded URI.
decodeURIComponent () decodes a coded URI component.
encodeURI () encodes the string as a URI.
encodeURIComponent () encodes the string as a URI component.
Escape () encodes a string
Code: |
var url = "Http://www.baidu.com?name= Zhang &password=12//3"; Alert (encodeURI (URL)); Http://www.baidu.com?name=%E5%BC%A0&password=123 Alert (encodeuricomponent (URL)); Http%3a%2f%2fwww.baidu.com%3fname%3dzhangsan%26password%3d123 Alert (Escape (URL)); Http%3a//www.baidu.com%3fname%3dzhangsan%26password%3d123 |
(2) Forced conversion
Number () Converts the value of the object to a digit.
String () Converts the value of the object to a string.
(3) Conversion to Digital
parseint () parses a string and returns an integer.
Parsefloat () parses a string and returns a floating-point number.
(4) eval () computes the JavaScript string and executes it as script code.
Code: |
var str = "var a=2;var b=3;alert (a+b)"; eval (str); function Print (str) { eval (str); } Print (" custom Logic "); |
The function in JS