代码语言:javascript 代码运行次数:0 运行 AI代码解释 varobj={};obj.valueOf=function(){return10;}obj.toString=function(){return"return value";}varresult=obj+1;//var result = obj.valueOf() + 1;alert(result);alert(obj);//alert(obj.toString()); (2)返回值类型的差别: toString一定将所有内...
此处之外,Array、Function并没有自己的原型valueOf方法,见规范说明: NOTE The Array prototype object does not have a valueOf property of its own; however, it inherits the valueOf property from the standard built-in Object prototype Object. The Function prototype object does not have a valueOf prope...
此处之外,Array、Function并没有自己的原型valueOf方法,见规范说明: NOTE The Array prototype object does not have avalueOfproperty of its own; however, it inherits thevalueOfproperty from the standard built-in Object prototype Object. The Function prototype object does not have avalueOfproperty of i...
7 }; 8 Object.prototype.valueOf= function(){ 9 console.log('proto valueof'); 10 return _pv.call(this); 11 } 12 var a={ 13 toString: function(){ 14 console.log('a tostring'); 15 return 'a'; 16 }, 17 valueOf: function(){ 18 console.log('a valueof'); 19 return 1; 20...
functionMyNumberType(n){this.number=n;}MyNumberType.prototype.valueOf=function(){returnthis.number;};varmyObj=newMyNumberType(4);myObj+3;// 7 规范 Specification Status Comment ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.1. ...
对象 操作 Array 将 Array 的元素转换为字符串。结果字符串由逗号分隔,且连接起来。 Boolean 如果 Boolean 值是 true,则返回 “true”。否则,返回 “false”。 Date 返回日期的文字表示法。 Error 返回一个包含相关错误消息的字符串。 Function 返回如下格式的字符串,其中 functionname 是被调用 ...
6) typeof函数的返回值:数字——number,字符串——string,布尔值——Boolean,对象、数组、null——object,函数名——function或undefined(未定义时)。主要用来区别区别对象和原始类型。要区分对象的具体类型,用instanceof运算符。 7) 在函数体内有隐含的arguments对象,可取得所有传入的参数,可用类似数组的方式读/写各...
prototype.valueOf = function() { return customPrimitiveValue; }; 有了这样的一个方法,下一次每当 myNumberType 要被转换为原始类型值时, JavaScript 在此之前会自动调用自定义的 valueOf 方法。 valueOf 方法一般都会被 JavaScript 自动调用,但你也可以像下面代码显示的那样自己去调用: myNumber.valueOf() ...
// create num1 object from customNum() constructor functionvarnum1 =newcustomNum(2);console.log(num1 +3);// Output: 5 Run Code In the above example, we have created a customvalueOf()method which overrides the built-invalueOf()method of JavaScript. This method returns the value from th...
View the example in the browser Supported Browser See also: JavaScript Core objects, methods, properties. Previous:JavaScript UTC() Method: Date Object Next:Javascript Function Objects - Properties and Methods Test your Programming skills with w3resource'squiz....