Javascript-检测参数

Posted 2021-02-26

// Detecting the existence of a parameter
/*
Example 1: The in operator
Detect whether there is a "myparameter" member in the "oArg" object: */
var myparameter = 'myparameter' in oArg? oArg.myparameter : "";
/*
Example 2: The typeof operator 
Detect whether type of oArg.myparameter is not "undefined': */
var myparameter = typeof oArg.myparameter != 'undefined'? oArg.myparameter : "";
/*
Example 2.1: The typeof operator version 2
Assuming parameter is a string, detect whether type of oArg.myparameter is "string": */
var myparameter = typeof oArg.myparameter == 'string'? oArg.myparameter : ""; 
/*
Example 3: Autocasting
Assign the value of oArg.myparameter to variable "myparameter" if it casts to true: */
var myparameter = oArg.myparameter || "";