Question

方法el.getBoundingClientRect()提供相对于视口左上角（0,0）的结果，而不是相对于元素的父级，而el.offsetTop ，el.offsetLeft（等）给出相对于父母的结果。

使元素的坐标相对于其父元素的最佳实践是什么？ el.getBoundingClientRect()已修改（如何？）将父级用作(0,0)坐标，或仍为el.offsetTop，el.offsetLeft等等？

Answer 1

您可以使用getBoundingClientRect()，只需减去父级的坐标：

var parentPos = document.getElementById('parent-id').getBoundingClientRect(),
    childrenPos = document.getElementById('children-id').getBoundingClientRect(),
    relativePos = {};

relativePos.top = childrenPos.top - parentPos.top,
relativePos.right = childrenPos.right - parentPos.right,
relativePos.bottom = childrenPos.bottom - parentPos.bottom,
relativePos.left = childrenPos.left - parentPos.left;

console.log(relativePos);
// something like: {top: 50, right: -100, bottom: -50, left: 100}

现在您拥有相对于其父级的子级坐标。

请注意，如果top或left坐标为负数，则表示子项在该方向上转义其父项。如果bottom或right坐标为正，则相同。

工作示例

var parentPos = document.getElementById('parent-id').getBoundingClientRect(),
    childrenPos = document.getElementById('children-id').getBoundingClientRect(),
    relativePos = {};

relativePos.top = childrenPos.top - parentPos.top,
relativePos.right = childrenPos.right - parentPos.right,
relativePos.bottom = childrenPos.bottom - parentPos.bottom,
relativePos.left = childrenPos.left - parentPos.left;

console.log(relativePos);

#parent-id {
    width: 300px;
    height: 300px;
    background: grey;
}

#children-id {
    position: relative;
    width: 100px;
    height: 200px;
    background: black;
    top: 50px;
    left: 100px;
}

<div id="parent-id">
    <div id="children-id"></div>
</div>

元素相对于其父级的坐标

1 个答案:

工作示例