Example of setting default parameter values in Javascript and javascript

Example of setting default parameter values in Javascript and javascript

First:

Function test (a, B) {var a = arguments [0]? Arguments [0]: 1; // set the default value of parameter a to 1var B = arguments [1]? Arguments [1]: 9; // set the default value of parameter B to 9 return a + B;

It is equivalent

Function test () {var a = arguments [0]? Arguments [0]: 1; // set the default value of parameter a to 1var B = arguments [1]? Arguments [1]: 9; // set the default value of parameter B to 9 return a + B ;}

Call example

Alert (test (); // output 10 alert (test (5); // output 14 alert (test (5, 6 )); // output 11 alert (test (null, 6); // output 7 alert (test (6, null); // output 15

Second:

Function test (blog, address) {blog = blog | 'forgot ~ Ash'; address = address | 'www .jb51.net'; alert (the address of 'blog name is '+ blog +' is '+ address );}

It is equivalent

Function test (blog, address) {if (! Blog) {blog = 'forgot ~ Ash';} if (! Address) {address = 'www .jb51.net';} alert (the 'blog name is '+ blog +' and the address is '+ address );}

Call example

Test (); // The blog name is forgotten ~ The source address is www. jb51.nettest ('csdn ', 'blog .csdn.net'); // If the blog name is csdn, the address is blog. csdn. nettest ('', 'blog .csdn.net/u011043843'); // The blog name is forgotten ~ Simple thinking

Third:

Function test (setting) {var defaultSetting = {name: 'programmer ', age: '1', phone: '000000', QQ: '000000', message: 'Welcome to add'}; $. extend (defaultSetting, setting); var msg = 'name: '+ defaultSetting. name + ', age:' + defaultSetting. age + ', tel:' + defaultSetting. phone + ', QQ group:' + defaultSetting. QQ + ', Description:' + defaultSetting. message + '. '; Alert (msg );}

Call example

Test (); // output: Name: programmer, age: 1, tel: 15602277510, QQ group: 259280570, note: welcome to join. Test ({name: 'dwqs ', age: '20', QQ: '000000', message: 'blog: www.jb51.net'}); // output: name: dwqs, age: 20, tel: 15602277510, QQ group: 461147874, note: Blog: www.jb51.net.

Ps: This method can be used if there are many function parameters. This is an extension of JQuery, so JQuery needs to be introduced.

In javascript, when a function has multiple parameters, how does one "enter only" specific parameters?

In the order of functions, the values before pay can be specified as null (if there is internal verification, enter the default value without errors), and the values after pay can be omitted.

For example:

Var Test = function (arg1, arg2, pay, arg3, arg4 ){...}

Can be called: Test (null, null, 'pay ');
 
Setting multiple parameters in javascript Functions

OnClick = "biaoji ('<% = xzuo %>', '<% = yzuo %>', '<% = zzuo %> ');"

Replace it with this.