<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
//示例1
var a = 1;
var b = a++; //先赋值后加减
var b = ++a; //先加减后赋值
alert(a);
alert(b);
//示例2
var x = 1;
alert(x++); //x = x + 1 1
alert(++x); //x = x + 1 3
alert(x--); //x = x - 1 2
alert(--x); //x = x - 1 2
alert(x) //1
//一元加减法
var a=3;
var a="3";
var a="3.2";
var a="123a456";
var a="123a";
var a="a123"
b = +a;
b =- a;
alert(b);
alert(typeof(b));
&& 逻辑与
1 && 0 //0
0 && 1 //0
0 && 0 //0
1 && 1 //1
|| 逻辑或
1 || 0 //1
0 || 1 //1
0 || 0 //0
1 || 1 //1
! 逻辑非
//示例1
var a=1;
if(a < 10 && a > 0){
++a;
alert(1);
}
//示例2
if (null && true){
alert(1);
}
//示例3
if ( 1 & 2){
alert("hello");
}
//示例四
alert(2==2);
alert(2=="2");
alert(2 === 2);
alert(25 < 3);
alert("ba2566545" < "bab3");
alert("25" < 3)
//示例五
alert(3 && 2)
//示例六
alert(true && 3)
</script>
</body>
</html>