This article mainly introduces the setting of the default parameter value in Javascript, which is very simple but practical. If you need it, refer to the first one:
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.