toFixed 把数字转换为字符串,结果的小数点后有指定位数的数字。 toExponential 把对象的值转换为指数计数法。 toPrecision 把数字格式化为指定的长度。 valueOf 返回一个 Number 对象的基本数字值。 6. Boolean 对象 属性 属性 描述 constructor 返回对创建此对象的 Boolean 函数的引用 prototype 使您有能力向对象添加...
JavaScript是一种解释执行的脚本语言,是一种动态类型、弱类型、基于原型的语言,内置支持类型,它遵循ECMAScript标准。它的解释器被称为JavaScript引擎,为浏览器的一部分,广泛用于客户端的脚本语言,主要用来给HTML增加动态功能。 几乎所有主流的语言都可以编译为JavaScript,进而能够在所有平台上的浏览器中执行,这也体现了Java...
lastName){ greetingMsg = greetingMsg + firstName + " " + lastName; } return { sendGreeting: function(firstName, lastName){ msgTo(firstName, lastName); } getMsg: function(){ return greetingMsg; } } } const createMsg = sayHello(); createMsg.send...
“Unexpected escaped character ‘{a}’ in regular expression.” : “在正则表达式中出现了没有转义的字符 ‘{a}’”, “Expected ‘{a}’ and instead saw ‘{b}’.” : “应该用 ‘{a}’代替’{b}’”, “Spaces are hard to count. Use {{a}}.” : “空格难以统计,请使用 {{a}}”, ...
> Number(true) 1 > parseFloat(null) // same as parseFloat('null') NaN > Number(null) 0 parseFloat()parses the empty string asNaN: > parseFloat('') NaN > Number('') 0 parseFloat()parses until the last legal character, meaning you get a result where you may not want one: ...
Another way to convert a string to a number is by using the parseInt() function. This function takes a string as its argument and returns an integer. If the string starts with a non-numeric character, parseInt() will return NaN. const str = "42"; const num = parseInt(str); console....
Number literals create number primitives, i.e numeric values that don't have any properties/methods attached to them. Consider the following code: JavaScript var x = 50.5; Here we create a variable x and then assign a numeric literal 50.5 to it. This literal creates a number primitive. So...
parseInt() tries to get a number from a string that does not only contain a number:parseInt('10 lions', 10) //10but if the string does not start with a number, you’ll get NaN (Not a Number):parseInt("I'm 10", 10) //NaN...
修改routes\games\GuessNumberRoute.js文件,将输入合法的数据传递给service,完成逻辑判断和猜数历史保存,修改后代码如下: //……constguessNumberService=require('../../services/games/GuessNumberService');//引入service模块//……router.post('/checknumber',function(req,res,next){letoutMsg={title:'猜数结果...
Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more.