++ 和 —

加加 和 减减

//运算后再++ 或--
i=j=3
i-- == 3//true
j++ -1+1 == 3//true

//先++ 或-- 再运算
i=j=4
--i == 4//false
--j -1+1 == 4//false

//没区别 (●'◡'●)
for(var i = 0; i < 2; ++i){console.log(i)}
for(var i = 0; i < 2; i--){console.log(i)}

Strict Equality Operator

Equality operator ==

两边的值先自动转为同一类型再比较

perform a type conversion，实施类型转换

使用typeof 查看变量类型，typeof '100' //string

Strict equality operator ===

严格相等，不进行类型转换

Inequality Operator

! = ≠

自动转换类型

! == ≠=

strict inequality operator，不进行类型转换

greater than operator 大于操作符

≥ greater than or equal to 大于等于操作符

< less than operator

≤ less than or equal operator

&& logical and operator

&& & || |

0、NaN、' '、null、undefined转换为boolean值都为flase

幂 (**) 幂运算符

var1 ** var2 var1的var2次方

a ** b ** c 等同于 a ** (b ** c)