前端杂记

脚本

1. uuid

       public generateUUID(): string {
           let p0 = `00000000${Math.abs((Math.random() * 0xFFFFFFFF) | 0).toString(16)}`.substr(-8);
           let p1 = `00000000${Math.abs((Math.random() * 0xFFFFFFFF) | 0).toString(16)}`.substr(-8);
           return `${p0}${p1}`;
       }
   

2. 保留小数点

   const toFixed = (n, fixed) => ~~(Math.pow(10, fixed) * n) / Math.pow(10, fixed);
   

css

1. 圆镂空效果

   html：
       <div id="back">
           <div id="circle"></div>
       </div>
   
   css：
       #back {
           position:absolute;
           top: 50%;
           transform: translateY(-50%);
           background: url('https://static.runoob.com/images/mix/img_tree.png');
           width: 200px;
           height: 200px;    
       }
   
       #circle {
           background: transparent;
           width: 100%;
           height: 100%;
           background-image: radial-gradient(circle, transparent 70%, gray 70%, gray 100%);
           opacity:0.7;
       }