5 JavaScript Set a Default Value for a Function Parameter 6 7 8 9 // Defining a function 10 functionsayHi(name='There') { 11 document.write('Hi, '+name+''); 12 } 13 14 sayHi();// Prints: Hi, There 15 sayHi('Peter...
The first function call doesn’t pass any parameters, so each is undefined. The second passes just the "a" parameter so that has a value and the others are undefined and so on. Setting a default value To specify a default value for a parameter in a Javascript function if it is not pa...
Now, to set a default parameter value for a JavaScript function we use the following way.Syntax:function functionName(param1 = default1, param2 = default2, ...) { // function body } A default value is set for the parameters in the function. While calling the function, if the ...
Topic:JavaScript / jQueryPrev|Next Answer: Use the Assign (=) Operator We all know that in JavaScript, function parameters default toundefined. However, it is often useful to specify a different default value for the parameter. Since ES6, you can simply use the assign (=) operator to ...
Default parameters can be really useful to ensure you have at least an empty array or object literal available when performing operations. Here’s an example with a default parameter: function addToGuestList(guests, list = []) { console.log([...guests, ...list]); } addToGuestList(['Bo...
#Using Default Value as Function Parameter Quite often you would see||being used like this: function(name){name=name||'no name';} Note: this is not the recommended way anymore. It's way better to ES6's default parameters. Because quite often, you might not want the default to kick in...
// [undefined, 5, 5, ":P", {value:"=^_^="}, arguments, "=^_^="] withoutDefaults.call({value: '=^_^='}); // [undefined, 5, 5, ":P", {value:"=^_^="}, arguments, "=^_^="] Scope Effects If default parameters are defined for one or more parameter, then asecond ...
在Dart中,常规的参数都是必传的,而命名参数和位置参数(positional parameter)都可以是可选参数。当然方法体中需要增加容错逻辑,已防止可选参数不传导致的报错。 可选命名参数: 代码语言:javascript 复制 intsum({int a,int b}){if(b==null)b=0;returna+b;}sum(a:3);// 3sum(a:3,b:4);// 7 ...
functionouter(parameter=functioninner(){return100}){returnparameter()}// Invoke outer functionouter()// 100 总结 在本文中,我们了解了什么是默认函数参数以及如何使用它们。现在,我们可以使用默认参数来帮助保持函数的整洁和易于阅读。还可以预先将空对象和数组分配给参数,以便在处理从对象中检索值或遍历数组等情...
Sometimes this is acceptable, but sometimes it is better to assign a default value to the parameter: Example functionmyFunction(x, y) { if(y === undefined) { y =2; } } Try it Yourself » Default Parameter Values ES6allows function parameters to have default values. ...