1、逻辑运算符--非布尔值的与或运算
对于非布尔值进行与或运算，会先将其转换为布尔值，然后再运算，并且返回原值
（1）&&
如果&&的左右操作数转换为布尔值后都为true，则返回右操作数
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res1 = 1 && 2;var res2 = 2 && 1;document.writeln("res1=" + res1);document.writeln("<br>");document.writeln("res2=" + res2);</script>
</head><body>
</body></html>结果：
如果两个值中有false，则返回靠前的false
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res1 = 0 && 2;var res2 = 1 && 0;document.writeln("res1=" + res1);document.writeln("<br>");document.writeln("res2=" + res2);</script>
</head><body>
</body></html>结果：
总结：如果左操作数为true,则必然返回第二个值；如果第一个值为false，则必然返回第一个值。
（2）||
如果第一个值为true，则直接返回第一个值
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res1 = 1 || 2;var res2 = 2 || 1;document.writeln("res1=" + res1);document.writeln("<br>");document.writeln("res2=" + res2);</script>
</head><body>
</body></html>结果：
如果第一个值为false，则直接返回第二个值
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res1 = 0 || 2;var res2 = 0 || 1;document.writeln("res1=" + res1);document.writeln("<br>");document.writeln("res2=" + res2);</script>
</head><body>
</body></html>结果：
总结：如果第一个值为true，则直接返回第一个值；如果第一个值为alse返回，则直接第二个值。
2、赋值运算符
赋值运算符:可以将符号右侧的值赋值给符号左侧的变量。
（1）=
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res = 12;//将12赋值给resdocument.writeln(res);</script>
</head><body>
</body></html>结果：
（2）+=
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res = 12;res += 5;//与res=res+5等价document.writeln(res);</script>
</head><body>
</body></html>结果：
（3）-=
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res = 12;res -= 5;//与res=res-5等价document.writeln(res);</script>
</head><body>
</body></html>结果：
（4）*=
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res = 12;res *= 5;//与res=res*5等价document.writeln(res);</script>
</head><body>
</body></html>结果：
（5）/=
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res = 12;res /= 5;//与res=res/5等价document.writeln(res);</script>
</head><body>
</body></html>结果：
（6）%=
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var res = 12;res %= 5;//与res=res%5等价document.writeln(res);</script>
</head><body>
</body></html>结果：
)