JavaScript数据类型相关知识详解

<script>
    // 整数字面量
    // 十进制
    console.log(12);
    // 八进制
    console.log(010);
    // 十六进制
    console.log(0x100);
</script

// 浮点数字面量
console.log(1.2);
console.log(-1.2);
console.log(0.1343);
console.log(.1343);
console.log(1.2e4);
console.log(1.2e-4);

// Infinity
console.log(Number.MAX_VALUE);
console.log(Number.MIN_VALUE);
console.log(5e789);
console.log(-5e789);
console.log(Infinity);

// NaN
console.log(0 / 0);
console.log(isNaN(0 / 0));
console.log(isNaN(22));

// 字符串字面量
console.log("这是一个'字符串'");
console.log("123");
console.log("000%$*^");
console.log("     ");
console.log("");

// 转义符
console.log("你\n好");
console.log("你\t好");
console.log("你好\"呀\"");

// 变量的定义
var name;
var userName;
var a;
var b1;

// 变量的定义
var name;
var userName;
var a;
var b1;

// 变量的赋值
var a=1,b=2,c=3;
a = a + b + c;
console.log(a);

console.log(typeof(6.8));
console.log(typeof(-1));
console.log(typeof(NaN));
console.log(typeof(false));
console.log(typeof 66);
console.log(typeof 66 + 3);

// 转成字符串类型
console.log(true.toString());
console.log(String(2333));
console.log(1 + "");

// 转换成数字类型
console.log(Number("11aa"));
console.log(parseInt("123.11ac")); //转换成整数
console.log(parseFloat("12.123hh"));

// 转成布尔类型
console.log(Boolean(NaN));
console.log(Boolean(""));
console.log(Boolean(undefined));
console.log(Boolean("   "));
console.log(Boolean(123));

// var num = prompt("请输入一个十以内的数字");
// num = parseInt(num);
// console.log(typeof(num));

// 简单化写法
var num = parseInt(prompt("请输入一个十以内的数字"));
num = num + 3;
console.log(num);