#range {    position: relative;    width: 600px;    height: 400px;    margin: 10px;    background-color: rgb(133, 246, 250);}.icon {    position: absolute;    height: 100px;    width: 100px;    cursor: move;    background-color: #ff9204;    user-select: none;}

<div id="range">    <div class="icon">100*100</div></div>

const main = document.getElementById('range');const icon = document.querySelector('.icon');let move = false;let deltaLeft = 0, deltaTop = 0;// 拖動開始事件，要綁定在被移動元素上icon.addEventListener('mousedown', function (e) {    /*    * @des deltaLeft 即移動過程中不變的值    */    deltaLeft = e.clientX-e.target.offsetLeft;    deltaTop = e.clientY-e.target.offsetTop;    move = true;})// 移動觸發事件要放在，區域控制元素上main.addEventListener('mousemove', function (e) {    if (move) {        const cx = e.clientX;        const cy = e.clientY;        /** 相減即可得到相對于父元素移動的位置 */           let dx = cx - deltaLeft        let dy = cy - deltaTop        /** 防止超出父元素范圍 */        if (dx < 0) dx = 0        if (dy < 0) dy = 0        if (dx > 500) dx = 500        if (dy > 300) dy = 300        icon.setAttribute('style', `left:${dx}px;top:${dy}px`)    }})// 拖動結束觸發要放在，區域控制元素上main.addEventListener('mouseup', function (e) {    move = false;    console.log('mouseup');})

.cus-canvas{    background: rgb(50, 204, 243);}.input-ele{    display: none;    position: fixed;    width: 180px;    border: 0;    background-color: #fff;}

<div>    <canvas id="canvas" class="cus-canvas"  width="800" height="600"></canvas>    <input id="inputEle" class="input-ele"/></div>

let mouseDown = false;let deltaX = 0;let deltaY = 0;let text = 'hello'const canvas = document.getElementById('canvas');const ctx = canvas.getContext('2d');const cw = canvas.width, ch = canvas.height;const rect = {    x: 20,    y: 20,    width: 150,    height: 50}/** 設置文字和邊框樣式 */ctx.font="16px Arial";ctx.fillStyle = "#fff"; /** 設置為 center 時，文字段的中心會在 fillText的 x 點 */ctx.textAlign = 'center';ctx.lineWidth = '2';ctx.strokeStyle = '#fff';strokeRect()const inputEle = document.getElementById('inputEle');inputEle.onkeyup =  function(e) {    if(e.keyCode === 13) {        text = inputEle.value        strokeRect()        inputEle.setAttribute('style', `display:none`)    }}canvas.ondblclick = function(e){     inputEle.setAttribute('style', `left:${e.clientX}px;top:${e.clientY}px;display:block`);    inputEle.focus();}canvas.onmousedown = function(e){     /** 獲取視口左邊界與canvas左邊界的距離 加上 鼠標點擊位置與canvas左邊界的長度，這個值是相對移動過程中不變的值 */    deltaX=e.clientX - rect.x;    deltaY=e.clientY - rect.y;    mouseDown = true};  const judgeW = cw-rect.width, judgeH = ch-rect.height;canvas.onmousemove = function(e){     if(mouseDown) {        /** 相減即可獲得矩形左邊界與canvas左邊界之間的長度 */        let dx = e.clientX-deltaX;         let dy = e.clientY-deltaY;         if(dx < 0) {            dx = 0;        } else if (dx > judgeW) {            dx = judgeW;        }        if(dy < 0) {            dy = 0;        } else if(dy > judgeH) {            dy = judgeH;        }        rect.x = dx;        rect.y = dy;         strokeRect()    }};  canvas.onmouseup = function(e){     mouseDown = false};  /** 清除指定區域 */function clearRect() {    ctx.clearRect(0, 0, cw, ch)}/** 畫矩形 */function strokeRect() {    clearRect()    /** 這里如果不調用 beginPath 歷史的矩形會重新被繪制 */    ctx.beginPath()     ctx.rect(rect.x, rect.y, rect.width, rect.height)    ctx.stroke();    // 設置字體內容，以及在畫布上的位置    ctx.fillText(text, rect.x + 70, rect.y + 30);}