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<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript 运算符</h1>
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<p>对数字和字符串相加，会返回字符串。</p>
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<p id="demo"></p>
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<script>
var x = 7 + 8;
var y = "7" + 8;
var z = "Hello" + 7;
document.getElementById("demo").innerHTML =
x + "<br>" + y + "<br>" + z;
</script>
​
</body>
</html>
​