使用js+h5 canvas實(shí)現(xiàn)圖片驗(yàn)證碼功能

<div class="login_code_box">
        <div class="login_code">
         <input type="text" name="login_code" id="login_code" placeholder="請(qǐng)輸入驗(yàn)證碼">
                
 
        </div>
        <canvas id="canvas" >
 
        </canvas>
     <!-- <img src="" alt="" title="看不清？單擊此處刷新" class="login_code_img" > -->
</div>

#canvas{
  width: 130px;
  height: 45px;
  display: inline-block;
  border: 1px solid #c9c9c9;
  border-radius: 5px;
  
}

//驗(yàn)證碼生成
let canvas=document.getElementById('canvas')//畫布對(duì)象
 
let show_num=[]//裝驗(yàn)證碼的數(shù)組
//產(chǎn)生隨機(jī)顏色
function randomColor(){
  var r= Math.floor( Math.random()*256);
  var g= Math.floor( Math.random()*256);
  var b= Math.floor( Math.random()*256);
  return "rgb("+r+","+g+","+b+") "
}
//畫布
function draw(show_num){
  let canvas_clientWidth=document.getElementById('canvas').clientWidth//畫布長(zhǎng)度
  let canvas_clientHeight=document.getElementById('canvas').clientHeight//畫布高度
  let context = canvas.getContext("2d")//畫布環(huán)境 創(chuàng)建 context 對(duì)象：
  canvas.width=canvas_clientWidth
  canvas.height=canvas_clientHeight
  let str="A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0,q,w,e,r,t,y,u,i,o,p,a,s,d,f,g,h,j,k,l,z,x,c,v,b,n,m";
  let astr=str.split(',');//分割字符串形成數(shù)組
  let sLength=astr.length;//數(shù)組長(zhǎng)度
  for (let i = 0; i <= 3; i++) {
    let j=Math.floor(Math.random()*sLength);//隨機(jī)索引
    let deg=Math.random()*30*Math.PI/180;//0-30隨機(jī)弧度
    let text=astr[j];//隨機(jī)字符
    show_num[i]=text//驗(yàn)證碼字符數(shù)組
    let x=10+i*20//x坐標(biāo)
    let y=20+Math.random()*8//y坐標(biāo)
    //位移 旋轉(zhuǎn)角度 顏色 文字 樣式開始位置
    context.font='bold 23px 微軟雅黑'
    context.translate(x, y);
    context.rotate(deg);
    context.fillStyle = randomColor();
    context.fillText(text,0,0)
    context.rotate(-deg)
    context.translate(-x,-y)
  }
  //驗(yàn)證碼顯示小點(diǎn)
  for(let i=0;i<=30;i++){
   context.strokeStyle=randomColor()//設(shè)置隨機(jī)色用小點(diǎn)的顏色
   context.beginPath();//開始一條路徑
   let m=Math.random()*canvas_clientWidth;
   let n=Math.random()*canvas_clientHeight;
   context.moveTo(m,n)//移動(dòng)
   context.lineTo(m + 1, n + 1);//添加一個(gè)新點(diǎn)，然后在畫布中創(chuàng)建從該點(diǎn)到最后指定點(diǎn)的線條
   context.stroke();//畫上面定義好的路徑
  }
  //驗(yàn)證碼顯示線條
  for (let i = 0; i < 8; i++) {
    context.strokeStyle=randomColor()
    context.beginPath()
    context.moveTo(Math.random()*canvas_clientWidth,Math.random()*canvas_clientHeight);
    context.lineTo(Math.random()*canvas_clientWidth,Math.random()*canvas_clientHeight)
    context.stroke()
    
  }
 
}
draw(show_num)
console.log(show_num);
 
canvas.onclick=()=>{
draw(show_num)
console.log(show_num);
}