工作中遇到的问题？

如何监听css外部引入字体是否加载完成，执行其他代码

document.fonts.ready.then(() => {})

sort()排序将"-"或undefined排序到最后

[].sort(fn) function fn (a,b){ return (b != '--' && b != null && b != undefined) - (a != '--' && a != null && a != undefined) || Number(b) - Number(a); }

监听多张图片加载完成之后执行某些操作

let mulitimg = ['https://www.javascriptc.com/vue3.js'],promiseAll = [],img=[];
let imgTotal = mulitimg.length;
for (let i = 0; i < imgTotal; i++) {
    promiseAll[i] = newPromise((resolve,reject) => {
        img[i] = new Image();
        img[i].src = mulitimg[i];
        img[i].onload = function () {
            resolve(img[i])
        }
    })
}
Promise.all(promiseAll).then(img => {})

html2canvas插件 图片不清晰问题

不能使用背景图，要是用img，特殊字体渐变色等不支持，溢出省略号，无法显示

js判断滑动方向

var startx, starty;
    //获得角度
    function getAngle(angx, angy) {
        return Math.atan2(angy, angx) * 180 / Math.PI;
    };
 
    //根据起点终点返回方向 1向上 2向下 3向左 4向右 0未滑动
    function getDirection(startx, starty, endx, endy) {
        var angx = endx - startx;
        var angy = endy - starty;
        var result = 0;
 
        //如果滑动距离太短
        if (Math.abs(angx) < 2 && Math.abs(angy) < 2) {
            return result;
        }
 
        var angle = getAngle(angx, angy);
        if (angle >= -135 && angle <= -45) {
            result = 1;
        } else if (angle > 45 && angle < 135) {
            result = 2;
        } else if ((angle >= 135 && angle <= 180) || (angle >= -180 && angle < -135)) {
            result = 3;
        } else if (angle >= -45 && angle <= 45) {
            result = 4;
        }
 
        return result;
    }
    //手指接触屏幕
    document.addEventListener("touchstart", function(e) {
        startx = e.touches[0].pageX;
        starty = e.touches[0].pageY;
    }, false);
    //手指离开屏幕
    document.addEventListener("touchend", function(e) {
        var endx, endy;
        endx = e.changedTouches[0].pageX;
        endy = e.changedTouches[0].pageY;
        var direction = getDirection(startx, starty, endx, endy);
        switch (direction) {
            case 0:
                console.log("未滑动！");
                break;
            case 1:
                console.log("向上！")
                break;
            case 2:
                console.log("向下！")
                break;
            case 3:
                console.log("向左！")
                break;
            case 4:
                console.log("向右！")
                break;
            default:
        }
    }, false);