单行代码技巧

//交换两个变量 || 解构
let a = 0
let b = 1
[a,b] = [b,a]
console.log(a,b) //1,0

//检查元素当前是否处于焦点（document.activeElement）
const elementIsInFocus = el => (el === document.activeElement)
elementIsInFocus(anvElement);

//两点计算角度
//弧
const radiansAngle = (p1,p2) => Math.atan2(p2.y - p1.y,p2.x - p1.x);
//角
const degreesAngle = (p1,p2) => Math.atan2(p2.y - p1.y, p2.x - p1.x) * 180 / Math.PI

//弧度转度数 度数转弧度 
const radsToDegs = (rad) => (rad * 180) / Math.PI
const degsToRads = (deg) => (deg * Math.PI)/180

//等一段时间
const wait = time => new Promise((resolve) => setTimeout(resolve,time))