A JavaScript function is executed when "something" invokes it (calls it). Example // Function to compute the product of p1 and p2 functionmyFunction(p1, p2) { returnp1 * p2; } Try it Yourself » JavaScript Function Syntax A JavaScript function is defined with thefunctionkeyword, followed...
Function Declarations Earlier in this tutorial, you learned that functions aredeclaredwith the following syntax: functionfunctionName(parameters) { code to be executed } Declared functions are not executed immediately. They are "saved for later use", and will be executed later, when they are ...
The construction above by the specification is syntactically incorrect (an expression statement cannot begin with a function keyword), but as we will see below, none of the implementations provide the syntax error, but handle this case, though, every in it’s own manner. 我们如果来告诉解释器:我...
The return statement. Syntax functionfunctionName(parameters){ code to be executed } Parameters ParameterDescription functionNameRequired. The name of the function. Naming rules: same as JavaScript variables. parametersOptional. A set of arguments (parameter names), separated by commas. ...
make:function(arg1, arg2) { return[this, arg1, arg2 ]; } }; JavaScript函数调用规则2 在一个使用方法调用语法,像 obj.myFunction()或者 obj['myFunction'](),这时this的值为obj 这是事件处理代码中bug的主要源头,看看这些例子 1 2 3 4
log(userName()) // 报错:Uncaught TypeError: userName is not a function // 翻译:userName 不是一个函数 // 3、对象的属性或方法不存在 const obj = undefined;// 为null也会报错 console.log(obj.userName); // 报错:Uncaught TypeError: Cannot read property 'userName' of undefined // 翻译:...
英文|https://javascript.plainenglish.io/in-depth-js-new-function-syntax-b1957c5dab69 JavaScript技术一直处于不断发展壮大中,如果你是前端开发人员或者JavaScript开发工程师,那么,今天这个知识点,你有必要认真了解一下,它就是“new Function”。 1、语...
functionmakeArray(arg1, arg2){ return[this, arg1, arg2 ]; } 最常用的方法,但不幸的,全局的函数调用 当我们学习Javascript时,我们了解到如何用上面示例中的语法来定义函数。 ,我们也知道调用这个函数非常的简单,我们需要做的仅仅是: 1 2 3 4 5...
new123//TypeError: number is not a funcvarobj={};obj.unknownMethod()// TypeError: obj.unknownMethod is not a function 上面代码的第二种情况,调用对象不存在的方法,会抛出TypeError错误。 (5)URIError URIError是URI相关函数的参数不正确时抛出的错误,主要涉及encodeURI()、decodeURI()、encodeURIComponent...
console.log(square(5)); // 25 function square(n) { return n * n; } 尽管square() 函数在声明之前被调用,但此代码的运行并没有任何错误。这是因为 JavaScript 解释器会将整个函数声明提升到当前作用域的顶部,因此上面的代码等价于: jsCopy to Clipboard // 所有函数声明实际上都位于作用域的顶部 functi...