<!DOCTYPE html>
<html>

<head>
    <title>演示</title>
    <style>
        .resizeBox {}

        table {
            width: 100%;
            border: 1px solid #000;
            border-collapse: collapse;
        }

        th {
            background: #ccc;
        }

        th,
        td {
            border: 1px solid #000;
        }
    </style>
</head>

<body>
    <div class="resizeBox">
        <table id="resizeTable">
            <thead>
                <tr>
                    <th>标题1</th>
                    <th>标题2</th>
                    <th>标题3</th>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td>第1行</td>
                    <td>第1行</td>
                    <td>第1行</td>
                </tr>
                <tr>
                    <td>第2行</td>
                    <td>第2行</td>
                    <td>第1行</td>
                </tr>
                <tr>
                    <td>第3行</td>
                    <td>第3行</td>
                    <td>第1行</td>
                </tr>
            </tbody>
        </table>
    </div>
</body>
<script>
    window.onload = function () {
        init('resizeTable')

        function init(id) {
            var i,
                self,
                table = document.getElementById(id),
                header = table.rows[0],
                tableX = header.clientWidth,
                length = header.cells.length;

            for (i = 0; i < length; i++) {
                header.cells[i].onmousedown = function () {
                    self = this;
                    if (event.offsetX >
                        self.offsetWidth -
                        10) {
                        self.mouseDown = true;
                        self.oldX = event.x;
                        self.oldWidth = self.offsetWidth;
                    }
                };
                header.cells[i].onmousemove = function () {
                    if (event.offsetX > this.offsetWidth - 10) {
                        this.style.cursor = 'col-resize';
                    } else {
                        this.style.cursor = 'default';
                    }
                    if (self == undefined) {
                        self = this;
                    }
                    if (self.mouseDown != null && self.mouseDown == true) {
                        self.style.cursor = 'default';
                        if (self.oldWidth + (event.x - self.oldX) > 0) {
                            self.width = self.oldWidth + (event.x - self.oldX);
                        }
                        self.style.width = self.width;
                        table.style.width = tableX + (event.x - self.oldX) + 'px';
                        self.style.cursor = 'col-resize';
                    }
                };
                table.onmouseup = function () {
                    if (self == undefined) {
                        self = this;
                    }
                    self.mouseDown = false;
                    self.style.cursor = 'default';
                    tableX = header.clientWidth;
                };
            }
        };
    }
</script>

</html>