前端技术学习

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操作符

算术运算符

运算符名称作用示例
+加法两个数相加1+2
-减法左边减去右边20 - 3
*乘法两个数相乘4 * 43
/除法右边除左边（左边除以右边）434 / 43
%求余左边分成右边数字相同的若干整数部分后，剩下的余数434 % 43
**幂去底数的指数次方2 ** 3
javascript
console.log(1 + 2); //3
console.log(20 - 3); //17
console.log(4 * 43); //172
console.log(434 / 43); //10.093023255813954
console.log(434 % 43); //4
console.log(2 ** 3); //8

Math.pow(7,3)相当于7**3

运算符优先级此处就不过多记录，想了解更多请参考此链接：运算符优先级

自增和自减运算符

a++,++a a++ 是先取值 后自增 ++a 是先自增 后取值

javascript
let a = 0;
console.log(a++); //0
let b = 0;
console.log(++b); //1
javascript
let a = 0;
let b = a++;
console.log(a, b); //1,0
let c = 0;
let d = ++c;
console.log(c, d); //1,1

赋值运算符

+=,-=,*=,/=

javascript
let x = 3;
x += 4;
console.log(x)  //7

let y = 3;
y -= 1;
console.log(y)  //2

let z = 3;
z *= 4;
console.log(z)  //12

let w = 12;
w /= 4;
console.log(w)  //3

比较运算符

===,!==,<,>,<=,>=

javascript
let a = 3;
let b = 3;
let c = "3";
let d = 4;
console.log(a === b); //true
console.log(a === c); //false
console.log(a !== b); //false
console.log(a > d); //false
console.log(a <= d); //true

=== 严格等于，类型和值都必须相同