js 实现div拖拽拉伸完整示例

<div class="resize" data-key="drag">
    <img src="../images/liya.jpg" alt="">
    <div class="line line-n" data-key="n"></div>
    <div class="line line-e" data-key="e"></div>
    <div class="line line-s" data-key="s"></div>
    <div class="line line-w" data-key="w"></div>
    <div class="point point-n" data-key="n"></div>
    <div class="point point-e" data-key="e"></div>
    <div class="point point-s" data-key="s"></div>
    <div class="point point-w" data-key="w"></div>
    <div class="point point-ne" data-key="ne"></div>
    <div class="point point-se" data-key="se"></div>
    <div class="point point-sw" data-key="sw"></div>
    <div class="point point-nw" data-key="nw"></div>
</div>

* {
    margin: 0;
    padding: 0;
}
.container {
    height: 100vh;
    background: #000;
    overflow: hidden;
    user-select: none;
}
.resize {
    position: relative;
    outline: 1px solid #1890ff;
    touch-action: none;
}
img {
    display: block;
    width: 100%;
    height: 100%;
    pointer-events: none;
}
.line {
    position: absolute;
}
.line-n {
    left: 0;
    top: -3px;
    width: 100%;
    height: 6px;
    cursor: n-resize;
}
.line-e {
    top: 0;
    right: -3px;
    width: 6px;
    height: 100%;
    cursor: e-resize;
}
.line-s {
    left: 0;
    bottom: -3px;
    width: 100%;
    height: 6px;
    cursor: s-resize;
}
.line-w {
    top: 0;
    left: -3px;
    width: 6px;
    height: 100%;
    cursor: w-resize;
}
.point {
    position: absolute;
    width: 6px;
    height: 6px;
    background: #1890ff;
}
.point-n {
    top: -3px;
    left: calc(50% - 3px);
    cursor: n-resize;
}
.point-e {
    right: -3px;
    top: calc(50% - 3px);
    cursor: e-resize;
}
.point-s {
    bottom: -3px;
    left: calc(50% - 3px);
    cursor: s-resize;
}
.point-w {
    left: -3px;
    top: calc(50% - 3px);
    cursor: w-resize;
}
.point-ne {
    top: -3px;
    right: -3px;
    cursor: ne-resize;
}
.point-se {
    bottom: -3px;
    right: -3px;
    cursor: se-resize;
}
.point-sw {
    left: -3px;
    bottom: -3px;
    cursor: sw-resize;
}
.point-nw {
    left: -3px;
    top: -3px;
    cursor: nw-resize;
}

// 获取dom
const box = document.querySelector('.resize');
// 声明全局变量
let width = 200, height = 160, minWidth = 100, minHeight = 80, isPointerdown = false,
    x = (window.innerWidth - width) * 0.5, y = (window.innerHeight - height) * 0.5,
    diff = { x: 0, y: 0 }, lastPointermove = { x: 0, y: 0 }, key = '', rect = null;
box.style.width = width + 'px';
box.style.height = height + 'px';
box.style.transform = 'translate3d(' + x + 'px, ' + y + 'px, 0px)';
const action = {
    drag: function () {
        x += diff.x;
        y += diff.y;
    },
    n: function (e) {
        if (rect.bottom - e.clientY > minHeight) {
            height = rect.bottom - e.clientY;
            y = e.clientY;
        }
    },
    e: function (e) {
        if (e.clientX - rect.left > minWidth) {
            width = e.clientX - rect.left;
        }
    },
    s: function (e) {
        if (e.clientY - rect.top > minHeight) {
            height = e.clientY - rect.top;
        }
    },
    w: function (e) {
        if (rect.right - e.clientX > minWidth) {
            width = rect.right - e.clientX;
            x = e.clientX;
        }
    },
    ne: function (e) {
        this.n(e);
        this.e(e);
    },
    se: function (e) {
        this.s(e);
        this.e(e);
    },
    sw: function (e) {
        this.s(e);
        this.w(e);
    },
    nw: function (e) {
        this.n(e);
        this.w(e);
    }
}
// 绑定事件
box.addEventListener('pointerdown', function (e) {
    isPointerdown = true;
    e.target.setPointerCapture(e.pointerId);
    lastPointermove = { x: e.clientX, y: e.clientY };
    key = e.target.dataset.key;
    rect = box.getBoundingClientRect();
});
box.addEventListener('pointermove', function (e) {
    if (isPointerdown) {
        const current = { x: e.clientX, y: e.clientY };
        diff.x = current.x - lastPointermove.x;
        diff.y = current.y - lastPointermove.y;
        lastPointermove = { x: current.x, y: current.y };
        action[key](e);
        box.style.width = width + 'px';
        box.style.height = height + 'px';
        box.style.transform = 'translate3d(' + x + 'px, ' + y + 'px, 0)';
        e.preventDefault();
    }
});
box.addEventListener('pointerup', function (e) {
    if (isPointerdown) {
        isPointerdown = false;
    }
});
box.addEventListener('pointercancel', function (e) {
    if (isPointerdown) {
        isPointerdown = false;
    }
});