JavaScript 拥有基于“事件循环”的运行时模型。 浏览完整的JavaScript 参考文档。 标准对象 了解Array、Boolean、Date、Error、Function、JSON、Math、Number、Object、RegExp、String、Map、Set、WeakMap、WeakSet等标准内置对象。 表达式和运算符 学习运算符instanc
闭包是由捆绑起来(封闭的)的函数和函数周围状态(词法环境)的引用组合而成。换言之,闭包让函数能访问它的外部作用域。在 JavaScript 中,闭包会随着函数的创建而同时创建。
事件循环模型的一个非常有趣的特性是,与许多其他语言不同,JavaScript 永不阻塞。 处理 I/O 通常通过事件和回调来执行,所以当一个应用正等待一个IndexedDB查询返回或者一个XHR请求返回时,它仍然可以处理其它事情,比如用户输入。 遗留的例外是存在的,如alert或者同步 XHR,但应该尽量避免使用它们。注意,例外的例外也是...
Bear in mind that you can store any item in an array — string, number, object, another variable, even another array. You can also mix and match item types — they don't all have to be numbers, strings, etc, just like this: var random = ['tree', 795, [0, 1, 2]];. 字符串...
28 Array.prototype.lastIndexOf() lastIndexOf() 方法返回指定元素(也即有效的 JavaScript 值或变量)在数组中的最后一个的索引,如果不存在则返回 -1。从数组的后面向前查找,从 fromIndex 处开始。 29 Array.prototype.map() Editorial review completed. 30 Array.prototype.pop() pop() 方法删除一个数组...
Standard built-in objects Function Properties Function.arguments [Translate] Function.arity [Translate] Function.caller [Translate] Function.displayName [Translate] Function.length Function.name [Translate] Function.prototype [Translate] Methods Function.prototype.apply() [Translate] Function.prototype.bind(...
【MDN学习】JavaScript 之 Promise JavaScript Pomise API 学习 Promise.xx 表示类方法 Promise.prototype.xxx 表示实例方法 一、Promise 构造函数 语法:new Promise(executor) executor 参数 接收双参数(resolve, reject), resolve 和 reject 分别是执行成功 与 失败的函数...
JavaScript is a very free-form language compared to Java. You do not have to declare all variables, classes, and methods. You do not have to be concerned with whether methods are public, private, or protected, and you do not have to implement interfaces. Variables, parameters, and function...
If an array is created using a literal in a top-level script, JavaScript interprets the array each time it evaluates the expression containing the array literal. In addition, a literal used in a function is created each time the function is called. Array literals are also Array objects. See...
Languages such as Java provide the ability to declare methods private, meaning that they can only be called by other methods in the same class. JavaScript does not provide a native way of doing this, but it is possible to emulate private methods using closures. Private methods aren't just ...