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var message = "hi", found = false, age = 29
1. Undefined 只有一个值,只声明未赋值的变量初始值都是undefined。
2. Null 只有一个值,是一个空对象指针,变量定义时如果将要用于保存对象,可将其初始化为null。
3.Boolean 有两个值true和false,转型函数Boolean()。
4. Number
var num1 = Number("javascript"); //NaN var num2 = Number(""); //0 var num3 = Number("0911"); //911 var num4 = Number(true); //1 var num1 = parseInt("123javascript"); //123 var num2 = parseInt(""); //NaN var num3 = parseInt(22.5); //22 var num4 = parseInt(70); //70 var num5 = parseInt(070); //56 八进制 var num6 = parseInt(0xf); //15 十六进制 var num1 = parseFloat("123javascript"); //123 var num2 = parseFloat("0xA"); //0 始终忽略前导零 var num3 = parseFloat(22.5); //22.5 var num4 = parseFloat(22.34.5); //22.34 var num5 = parseFloat(070.5); //70.5 var num6 = parseFloat(3.125e7); //31250000
5. String
6. Object
var o = new Object()
The text was updated successfully, but these errors were encountered:
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JavaScript入门
1. JavaScript是一种为网页交互而设计的交互语言,由以下三部分组成:
2. < script >标签的六个参数
JavaScript基本语法
语法
变量
var message = "hi", found = false, age = 29
数据类型
1. Undefined
只有一个值,只声明未赋值的变量初始值都是undefined。
2. Null
只有一个值,是一个空对象指针,变量定义时如果将要用于保存对象,可将其初始化为null。
3.Boolean
有两个值true和false,转型函数Boolean()。
4. Number
5. String
6. Object
var o = new Object()
The text was updated successfully, but these errors were encountered: