address:"中国香港"};console.log(typeof(user));console.log(typeof(null));console.log(typeof(undefined));console.log(user.name);console.log(user.age);if(user.age){console.log(user.age);}else{console.log("没有age属性");}//为false的情况vari;console....
function (name) { let sex; const pet = { // 在这个上下文中:setName(newName) 等价于 setName: function (newName) setName(newName) { name = newName; }, getName() { return name; }, getSex() { return sex; }, setSex(newSex) { if ( typeof newSex === "string" && (newSex...
ThecharAt()method returns the character at a specified index (position) in a string. The index of the first character is 0, the second 1, ... See Also: The charCodeAt() Method The codePointAt() Method The indexOf() Method The lastIndexOf() Method ...
sayHello(firstName, lastName){ let msg = "Greetings "; function intro(){ return msg + firstName = " " + lastName; } return into(); } sayHello("Professor" , "Falken"); //returns "Greetings Professor Falken"; Listing 5-8Using a Closure to Illustrate an Inner Function’s Access to ...
In JavaScript, first character in the string has position 0, the second one 1, etc. So if you searched for “m”, indexOf method would return 0. If the searched text isn’t found, the method would return -1.Copy if (mailAddress.indexOf("@") == -1) { alert("Character @ wasn...
与其他语言相比,函数的 this 关键字在 JavaScript 中的表现略有不同,此外,在严格模式和非严格模式之间也会有一些差别。
string.substr(start,length) Parameters ParameterDescription startRequired. The start position. First character is at index 0. Ifstartis greater than the length, substr() returns "". Ifstartis negative, substr() counts from the end of the string. ...
ECMAScript 中有 5 种简单数据类型(也称为基本数据类型):Undefined、Null、Boolean、Number和 String。还有 1 种复杂数据类型——Object,Object 本质上是由一组无序的名值对组成的。 typeof操作符 鉴于ECMAScript 是松散类型的,因此需要有一种手段来检测给定变量的数据类型——typeof 就 是负责提供这方面信息的操...
/*! jQuery FineUI v3.5.0.1 | http://fineui.com/ */ (function () { var n = !1, t = /xyz/.test(function () { xyz }) ? /\b_super\b/ : /.*/; this.Class =
range.selectNode(document.getElementsByTagName("div").item(0)); const returnValue = range.comparePoint(document.getElementsByTagName("p").item(0), 1); 3.6. createContextualFragment() createContextualFragment(tagString):返回一个 DocumentFragment。