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@@ -0,0 +1,46 @@
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+<!DOCTYPE html>
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+<html lang="en">
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+<head>
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+ <meta charset="UTF-8">
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+ <meta name="viewport" content="width=device-width, initial-scale=1.0">
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+ <title>Document</title>
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+</head>
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+<body>
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+ <script>
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+ // 算数运算 + - * / %(取余/取模)
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+ // console.log(1+1);//2
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+ // console.log(1+'100'); //number + string 拼接
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+ // console.log(1 + true); //2
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+ // console.log(1 + false); //1
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+ // console.log(1 + undefined); //NaN 非法数字
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+ // console.log(1 + null); //1
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+ var a = 20;
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+ console.log("我今年"+a+"岁");
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+
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+ // console.log(1-1);//0
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+ // console.log(1-'100');//-99
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+ // console.log(1 - true); //0
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+ // console.log(1-undefined);//NaN
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+ // console.log(1-null);//1
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+
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+ // console.log(1*2);//2
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+ // console.log(1*'2');//2
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+ // console.log(2*false);//0
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+ // console.log(2*null);//0
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+ // console.log(2*undefined);//NaN
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+
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+ // console.log(10/2);//5
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+ // console.log(10/'2');//5
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+ // console.log(30/false);//Infinity
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+ // console.log(30/null);//Infinity
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+ // console.log(30/undefined);//NaN
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+
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+ console.log(11%3);//2
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+ console.log(11%'3');//2
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+ console.log(11%false);//NaN
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+ console.log(11%null);//NaN
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+ console.log(11%undefined);//NaN
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+
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+ </script>
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+</body>
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+</html>
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