How to implement anchor sliding in WeChat applet by using scroll-view

This article mainly introduces the example of implementing anchor sliding in the WeChat applet scroll-view. The editor thinks it is quite good, so I will share it with you now and give it as a reference. Let’s follow the editor and take a look.

Preface

I recently started making small programs. It’s not difficult to read through the documentation and get started, but I have to say that in the small programs There are still some pitfalls. Let’s talk about how to implement page anchor jump. The effect of a city list is as follows:

Because in the environment of WeChat applet, you cannot set tags in the browser , or operate dom scrolling, the traditional method will not work, everything must be done according to the mini program's documentation.

Our initial approach is to use the boundingClientRect() method to obtain the coordinates of each anchor point, and then use the wx.pageScrollTo() method to slide over. It turns out that the effect is not very good, because the coordinates of each point returned by the boundingClientRect method will change as the screen slides, which may also cause the page to jitter. In the end, the scroll-view (scrollable view area) component was chosen to achieve the anchor point effect. .

Specific implementation

I won’t go into details about the specific API. You can read the official documentation. Here are a few things to pay attention to. Here is a schematic scroll-view Component code, the above attributes are necessary: ​​

<scroll-view scroll-y style="height: 200px;" bindscroll="scroll" scroll-into-view="{{toView}}" >

scroll-into-view: This is bound to an attribute, its value should be the id of the page element, and you can jump by setting its value Go to the element corresponding to the ID.

scroll-y: Add this attribute to indicate vertical sliding, and the corresponding scroll-x indicates horizontal sliding. When sliding vertically, scroll-view must set a fixed height

bindscroll : Monitor the sliding, pass it an event, and execute the event when sliding

There are many attributes given in the document. For the time being, only the above few are needed to achieve the effect we want. The implementation principle is also very simple. In the content part, each English abbreviation of the view is set with an id, and then when clicking on the navigation list, the value of scroll-into-view is set to the clicked id to realize the jump.

Let’s talk about the height of scroll-view. This must be a fixed height for adaptation, otherwise the display effect will be different on mobile phones with different screen sizes.

Some optimizations

The functions have been basically implemented here, but some problems were discovered later: If you want to hide the scroll bar of scroll-view, you need to set the css style :::-webkit-scrollbar

::-webkit-scrollbar {
 width: 0;
 height: 0;
 color: transparent;
}

Also, you can click an anchor point to jump. At this time, if you scroll the page and click the anchor point you clicked before, the page will not jump again. This When scrolling, you need to listen to the scroll event and clear the value of the scroll-into-view attribute when scrolling. Or after each anchor point jump, an asynchronous operation will clear the value of the scroll-into-view attribute.

2017/12/05 addition:

scroll-view has no sliding animation by default. The animation effect that requires scrolling needs to be set on the component: scroll-with- animation='true'
Regarding the setting of fixed height height, at first I thought that this height was related to the number/height of scrolling elements. At this time, it is very troublesome to deal with dynamically changing lists. A method I saw later on the Internet is to use the wx.getSystemInfo method to get the windowHeight, and set this to the height of the scroll-view (unit: px).

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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