canvas原生实现前端网页移动端签名-

let c = document.getElementById("canvas")
let canvas = document.createElement("canvas")
let availHeight = document.documentElement.clientHeight
let off = availHeight - 400
canvas.height = &＃39;350&＃39;
canvas.width = c.clientWidth
c.appendChild(canvas)
let dr = canvas.getContext(&＃39;2d&＃39;)
dr.strokeStyle = &＃39;blue&＃39;
canvas.addEventListener(&＃39;touchstart&＃39;,(e)=>{
  dr.beginPath()
  dr.moveTo(e.changedTouches["0"].pageX,e.changedTouches["0"].pageY-off)
})
canvas.addEventListener(&＃39;touchmove&＃39;,(e)=>{
  dr.lineTo(e.changedTouches[0].pageX, e.changedTouches[0].pageY-off)
  dr.stroke()
})
canvas.addEventListener(&＃39;touchend&＃39;,(e)=>{
  dr.closePath()
})

生成图片

let img = document.querySelector(&＃39;canvas&＃39;).toDataURL()

如需发送给后端，可以让后端支持base64或者blob、buffer