arguments 被称为类数组对象(array-like object),因为它具有数字索引和 length 属性,但并不继承自 Array.prototype。我们可以通过索引访问各个参数,例如 arguments[0] 表示第一个参数,arguments[1] 表示第二个参数,依此类推。 从浏览器引擎的角度看,arguments 对象的内存结构通常由两部分组成:一部分是参数映射表,另...
JavaScript - arguments object Theargumentsobject is anArray-like object corresponding to the arguments passed to a function. functionfunc1(a, b, c) { console.log(arguments[0]);//expected output: 1console.log(arguments[1]);//expected output: 2console.log(arguments[2]);//expected output: 3...
When you learn to program in JavaScript, you learn to name the arguments that you pass into a function. I am going to show you why you should pass your arguments to a function as an object. Once you see why you will never go back to naming every argument you pass into a function. ...
functionfunc(a=55){a=99;// updating a does not also update arguments[0]console.log(arguments[0]);}func(10);// 10 并且 js functionfunc(a=55){console.log(arguments[0]);}func();// undefined 规范 Specification ECMAScript® 2026 Language Specification ...
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/arguments 二、总结 argumentsis anArray-like objectaccessible insidefunctionsthat contains the values of the arguments passed to that function. 1)argument in arguments can easily be get、set or reassigned ...
JavaScript 1 ["A", "a", 0, Object] 乍一看,结果是个数组,但并不是真正的数组,所以说 arguments 是一个类数组的对象(想了解真正数组与类数组对象的区别可以一直翻到最后)。 再看看 arguments 表示的内容,其表示了函数执行时传入函数的所有参数。在上面的例子中,代表了传入printArgs函数中的四个参数,可以分别...
JavaScript 中每个函数内都能访问一个特别变量 arguments。这个变量维护着所有传递到这个函数中的参数列表。 arguments 变量不是一个数组(Array)。 尽管在语法上它有数组相关的属性 length,但它不从 Array.prototype 继承,实际上它是一个对象(Object)。 (注意: 由于 arguments 已经被定义为函数内的一个变量。 因此通...
我们先用一个例子直观了解下 JavaScript 中的 arguments 长什么样子。 functionprintArgs(){console.log(arguments);}printArgs("A","a",0,{foo:"Hello, arguments"}); 执行结果是: ["A", "a", 0, Object] 乍一看,结果是个数组,但并不是真正的数组,所以说 arguments 是一个类数组的对象(想了解真正数...
first: nice nicesecond: JavaScript JavaScriptthird: secrets secrets If the function is called with more arguments than were declared in the function signature, this is the way to access them. However, the modern way is to use the rest parameter (…param) instead of the arguments object. ...
MDN-argumentsJavaScript arguments 对象全面介绍 arguments的性能问题 For performance, it appears that accessing named arguments is also faster than accessing the arguments object in all the major browsers. In this jsperf performance test that just sums the first three arguments passed to a test function...