How to set and control the scroll bar position in javascript

In front-end development, it is often necessary to set the scroll bar position of the page so that the specified position can be accurately positioned when the page is scrolled. In JavaScript, you can set and control the position of the scroll bar through some methods. This article will introduce these methods.

Get the scroll bar position

Before setting the scroll bar position, you first need to get the scroll bar position of the current page. In JavaScript, you can get the scroll bar position through the following two properties:

• window.pageXOffset or window.scrollX: Get the horizontal scrolling of the page bar position.
• window.pageYOffset or window.scrollY: Get the vertical scroll bar position of the page.

These two properties return numerical values, representing pixel values. For example, if the page scrolls down 100 pixels, the value of window.pageYOffset will equal 100.

Set the scroll bar position

After obtaining the scroll bar position, you can use some methods to set the scroll bar position.

scroll() method

scroll() method can be used to set the scroll bar position of the page. This method accepts two parameters: horizontal scrolling distance and vertical scrolling distance, corresponding to the scrollLeft and scrollTop properties of the page respectively. For example, the following code sets the scroll bar position of the page to scroll 100 pixels horizontally and 200 pixels vertically:

window.scroll(100, 200);

scrollTo() method

scrollTo()# The ## method is similar to the scroll() method and can also be used to set the scroll bar position of the page. However, the scrollTo() method is more commonly used because it can accept an object as a parameter to control the scroll bar position more flexibly. This object contains two properties: left and top, which correspond to the scrollLeft and scrollTop properties of the page respectively. For example, the following code sets the scroll bar position of the page to scroll 100 pixels horizontally and 200 pixels vertically:

window.scrollTo({ left: 100, top: 200 });

scrollBy() method

scrollBy()# The ## method is also used to set the scroll bar position of the page, but unlike the first two methods, the parameters of the scrollBy() method represent the relative scrolling distance, not the absolute scrolling distance. For example, the following code scrolls the page 100 pixels vertically: <pre class="brush:php;toolbar:false">window.scrollBy(0, 100);</pre>scrollIntoView() method

scrollIntoView()

method scrolls the specified element into the visible area. This method accepts a Boolean value as an optional parameter, indicating whether to use animation effects to scroll to the specified position. For example, the following code scrolls the first paragraph element in the HTML document to the visible area: <pre class="brush:php;toolbar:false">document.getElementsByTagName('p')[0].scrollIntoView();</pre>In the above code, if the optional parameters are not used, there will be no animation effect by default.

Compatibility issues

When using the above method to set the scroll bar position, you need to pay attention to the compatibility issues of different browsers. Among them, IE browser supports setting the scroll bar position to a decimal value, but other mainstream browsers do not support it. If you need to achieve consistent effects in different browsers, you can use the following method:

function setScrollPosition(left, top) {
    if (typeof window.scrollTo === 'function') {
        window.scrollTo(left, top);
    } else if (typeof document.documentElement.scrollTop === 'number' && typeof document.documentElement.scrollLeft === 'number') {
        document.documentElement.scrollTop = top;
        document.documentElement.scrollLeft = left;
    } else {
        document.body.scrollTop = top;
        document.body.scrollLeft = left;
    }
}

This method will first determine whether the browser supports the

scrollTo()

method. If it does, call it directly. This method sets the scroll bar position; otherwise, use the scrollTop and scrollLeft properties to set the scroll bar position.

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