This article mainly introduces three methods for setting default parameter values for functions in js, which have reference value, if you are interested, you can refer to how to set default parameter values for functions in javascript. Below are several methods for your reference.
Method 1:
Function example (a, B) {var a = arguments [0]? Arguments [0]: 1; // set the default value of parameter a to 1 var B = arguments [1]? Arguments [1]: 2; // set the default value of parameter B to 2 return a + B ;}
Note that the above functions can also be written as follows:
Function example () {var a = arguments [0]? Arguments [0]: 1; // set the default value of the first parameter to 1 var B = arguments [1]? Arguments [1]: 2; // set the default value of the second parameter to 2 return a + B ;}
Call example:
Alert (example (); // output 3 alert (example (10); // OUTPUT 12 alert (example (10, 20 )); // output 30 alert (example (null, 20); // output 20
Method 2:
Function example (name, age) {name = name | 'mink xy'; age = age | 21; alert ('Hello! I am '+ name +', and I am '+ age +' years old. ');}
This function can also be written as follows:
Function example (name, age) {if (! Name) {name = 'mink xy';} if (! Age) {age = 21;} alert ('Hello! I am '+ name +', and I am '+ age +' years old. ');}
Call example:
Example ('wang wu'); // output: Hello! I'm Wang Wu, 21 years old. Example ('wang wu', 30); // output: Hello! I'm Wang Wu, 30 years old. Example (null, 30); // output: Hello! I'm a 30-year-old.
The third method is suitable for scenarios with many parameters. Jquery extensions are used:
Function example (setting) {var defaultSetting = {name: 'red', age: '30', sex: 'female ', phone: '123', QQ: '123 ', birthday: '2017. 10.01 '}; $. extend (defaultSetting, settings); var message = 'name: '+ defaultSetting. name + ', Gender:' + defaultSetting. sex + ', age:' + defaultSetting. age + ', tel:' + defaultSetting. phone + ', QQ:' + defaultSetting. QQ + ', birthday:' + defaultSetting. birthday + '. '; Alert (message );}
Call example:
Example ({name: 'xiaohong', sex: 'female ', phone: '000000'}); // output: name: Xiaohong, Gender: female, age: 30, tel: 100866, QQ: 100866.
Have you learned the above three methods? These three methods have their own advantages and disadvantages. You can analyze the specific situation and select the most suitable method for learning.