If a function is called withmissing arguments(less than declared), the missing values are set toundefined. Sometimes this is acceptable, but sometimes it is better to assign a default value to the parameter: Ex
If a function is called with missing arguments (less than declared), the missing values are set to: undefined Sometimes this is acceptable, but sometimes it is better to assign a default value to the parameter:Example function myFunction(x, y) { if (y === undefined) { y = 0; } }...
You can observe that the type of parameters is not defined. We multiply the parameter values in the function body and return the resultant value.While calling the function, we passed 4 number values as a function argument. Users can observe the output of the function for the different ...
参数的检查和验证:在函数内部,最好对参数进行类型和有效性检查,以避免潜在的错误。 functionprocess(value){if(typeofvalue!=='number'){thrownewError('Parameter must be a number.');}console.log(value*2);}try{process(10);// 输出: 20process('test');// 抛出错误}catch(error){console.error(error...
setRequestHeader('Content-Type', 'application/json'); xhrSend.send(JSON.stringify({ UserName: usernameStr })); //---同步写法---onload xhrSend.onload = function () { if (xhrSend.status == 200) { console.log('--sendTest-接收:' + xhrSend.responseText); var data = JSON.parse(xhrSen...
function(parameter list){ staments }; 与命名函数的区别是没有函数名,函数后面有个分号。 当通过这种语法格式定义了函数之后,实际上就定义了一个函数对象(即function实例),接下来可以将这个对象赋给另外一个变量。例如下面代码: 1 2 3 4 5 6 7
const foo = function(index = 0, testing = true) { /* ... */ } foo()Default parameter values have been introduced in ES2015, and are widely implemented in modern browsers.This is a doSomething function which accepts param1.const doSomething = (param1) => { }...
empty stringDo not set the important qualifier for the property. Thenullvalue can also be used. Return value: This method has no return value. Example HTML code 1: This example illustrates the use of thesetPropertymethod: functionModifyBGColor (button) {if(button.style.setProperty) { button....
17.JS中的函数定义:function functionName([parameter],...){statement[s] 18.当文件中出现多个form表单时.可以用document.forms[0],document.forms[1]来代替. 19.窗口:打开窗口window.open(), 关闭一个窗口:window.close(), 窗口本身:self 20.状态栏的设置:window.status="字符"; ...
The alternative to passing a string as the first argument to these methods is to instead pass in afunction. Let’s look at an example. Here, then, would be a fairly typical use ofsetIntervalandsetTimeout, passing astringas the first parameter: ...