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其他参考手册

CSSStyleDeclaration JS 类型转换


Element offsetTop 属性

❮ Element 对象

实例

获取 div 元素的顶部偏移量:

var testDiv = document.getElementById("test");
document.getElementById("demo").innerHTML = testDiv.offsetTop;
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定义和用法

offsetTop 是一个只读属性,返回当前元素相对于 offsetParent 节点顶部边界的偏移像素值。

返回值包含:

  • 元素顶部偏移的像素值,元素的外边距(margin)
  • offsetParent 元素的顶部内边距(padding)、边框(border)及滚动条

注释: offsetParent 元素是一个指向最近的(指包含层级上的最近)包含该元素的定位元素或者最近的元素。

提示: 获取元素左侧的偏移量使用 use the offsetLeft 属性。


浏览器支持

属性
offsetTop Yes 8.0 Yes Yes Yes

语法

返回顶部偏移位置:

object.offsetTop


技术细节

默认值: no default value
返回值: 一个整数,表示该元素的顶部偏移量,单位是像素 px。
DOM 版本: CSSOM

更多实例

实例

获取 div 元素的位置:

var testDiv = document.getElementById("test");
var demoDiv = document.getElementById("demo");
demoDiv.innerHTML = "offsetLeft: " + testDiv.offsetLeft + "<br>offsetTop: " + testDiv.offsetTop;
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实例

创建一个粘性导航栏:

// Get the navbar
var navbar = document.getElementById("navbar");

// Get the offset position of the navbar
var sticky = navbar.offsetTop;

// Add the sticky class to the navbar when you reach its scroll position. Remove the sticky class when you leave the scroll position.
function myFunction() {
  if (window.pageYOffset  >= sticky) {
    navbar.classList.add("sticky")
  } else {
    navbar.classList.remove("sticky");
  }
}
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❮ Element 对象