JavaScript adaptive width waterfall flow implementation ideas_javascript skills

Such a layout is not unfamiliar. Since the establishment of Pinterest in 2011, the Chinese Internet has quickly set off a craze to imitate Pinterest. There are many domestic websites that use the waterfall flow layout, such as Huaban.com, Meilishuo, etc. In fact, on the Chinese Internet, imitating some models that are favored abroad (of course, you can also call them copycats or plagiarisms, haha!!) has always been a good idea.

OK, now let’s get to the point. Here we mainly introduce an implementation method of waterfall flow: absolute positioning (css) javascript ajax json. To put it simply, if you don't do scrolling loading, it is absolute positioning (css) javascript. Ajax and json are used when scrolling to load more content.

The following is the implementation idea:

1. Calculate the width of the page and the number of columns in which data blocks can be placed on the page (as shown in the figure above, there are 6 columns).

2. Record the height dimensions of each data block into the array (you need to wait until all images are loaded, otherwise the height of the image cannot be known).

3. Use absolute positioning to first fill the first row of the page, because the top position of the first row is the same, and then use an array to record the total height of each column.

4. Continue to use absolute positioning to position other data blocks after the shortest column and then update the height of the column.

5. When the browser window size changes, perform the above steps 1-4 again to rearrange (the number of columns changes with the page width, so it needs to be rearranged).

6. When the scroll bar scrolls to the bottom, new data is loaded and positioned at the position of the shortest column, and then the height of the column is updated.

The idea is there, and then it’s about how to implement it with code. Of course, if you already know how to implement it after reading the above 6 steps, then you don’t need to read the following content in detail.

First write the basic HTML and CSS on the page (for convenience, the CSS will not be externally linked). The code is as follows:

Copy code The code is as follows:

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The above code is very simple. It can be seen that the page will initially load 20 data blocks. It is worth mentioning that the opacity is defined as 0 in CSS. The purpose is to hide the data block before it is discharged. After the data block is discharged, the opacity is set to 1 to display it. In addition, the transition of css3 is used here for a little experience. Upgrade; another point is that you can see a DIV with the id "loading" at the bottom of the page, which indicates that the data is loading. Let’s start using JS to implement the above ideas (6 steps).

1. Calculate the width of the page and the number of columns in which data blocks can be placed on the page

Copy code The code is as follows:

The comments are very clear, and it should be easy to understand without explaining this step.

2. Record the height dimensions of each data block into the array

Copy the code The code is as follows :

Since the data block contains pictures and the size of the picture is not given, you need to wait for the picture to be loaded before you can obtain its height; then you can call the flow method during window.onload. The code becomes:

Copy the code The code is as follows:

3. Use absolute positioning to first fill the first row of the page, because the top position of the first row is the same, and then use an array to record each column. the total height.

Copy code The code is as follows:

as of So far, you can preview the effect in the browser:

OK, let’s start placing other data blocks, which is the fourth step of the idea.

4. Continue to use absolute positioning to position other data blocks at the position of the shortest column and then update the height of the column.

Copy code The code is as follows:

At this step, you can go to the browser to see the effect again. It can be said that the prototype of the entire waterfall flow has come out:

5. When the size of the browser window changes, perform the above steps 1-4 again to rearrange it

This step is also very convenient. When changing the window size, just execute the flow method again

Copy code The code is as follows:

What is worth noting here is setTimeout. Since the trigger frequency of onresize is very high, setting an interval with setTimout can reduce the execution frequency of the flow method and reduce performance loss.

6. When the scroll bar scrolls to the bottom, new data is loaded and positioned at the position of the shortest column and then updates the height of the column.

Copy code The code is as follows:

This step involves a lot of code. A simple summary is that there are several more methods: scroll(), _addItem(), _request(), _appendhtml().

Mainly look at scroll(). Here _addItem() and _requeat() are called by scroll(), and _appendhtml() is called by _addItem().

The whole process of this step is: when the page scrolls to the bottom of the shortest column of data, an ajax request is issued to load new data, and then after all the images in the data are loaded, they are appended to the page, and then the data The height of the item is written into the array lenArr, and the newly added data items are positioned and arranged in the appropriate position according to the rule that each item is placed behind the shortest column. Finally, the loading image is moved downwards. to the bottom position.

To summarize the entire idea above, there are 4 places worth mentioning :

1. When zooming the browser window, onresize is triggered very frequently. In order to reduce performance loss, it is necessary to wait for the zoom to be completed before performing the reordering. The above idea is to use setTimeout to handle it.

2. When the page scrolls to the bottom to load new data, you only need to arrange the new data.

3. In the above idea, when loading new data, you need to wait until the images are loaded to know their height. However, in actual projects, it is best for the server to give the height value.

4. When scrolling triggers the loading of new data, avoid multiple triggering of the event. The above idea is to set the onscroll event to empty, and then restore the event after the loading is completed.

Attach the complete code at the end:
flow.html

Copy the code The code is as follows :

 

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GetList.php

Copy code The code is as follows:

header("Content-Type:application/json;charset=utf-8");
echo('{"d": [
{ "img": "http://www.mitxiong.com/NewsImages/2012121821504156.jpg", "title": "Picture 1"},
{"img": "http://www.mitxiong.com /NewsImages/2012112718241731.jpg", "title": "Picture 2"},
{"img": "http://www.mitxiong.com/NewsImages/2012111806582944.jpg", "title": "Picture 3"},
{"img": "http://www.mitxiong.com/NewsImages/2012110907231232.jpg", "title": "Picture 4"},
{"img": "http ://www.mitxiong.com/NewsImages/2012110406319529.jpg", "title": "Picture 5"},
{"img": "http://www.mitxiong.com/NewsImages/2012101808066955.jpg ", "title": "Picture 6"},
{"img": "http://www.mitxiong.com/NewsImages/2012101307276582.jpg", "title": "Picture 7"},
{"img": "http://www.mitxiong.com/NewsImages/2012082223432719.jpg", "title": "Picture 8"},
{"img": "http://www.mitxiong .com/NewsImages/2012082121509065.jpg", "title": "Picture 9"},
{"img": "http://www.mitxiong.com/NewsImages/2012081922387254.jpg", "title": "Picture 10"},
{"img": "http://www.mitxiong.com/NewsImages/2012081700252403.jpg", "title": "Picture 11"},
{"img": "http://www.mitxiong.com/NewsImages/2012081407597304.jpg", "title": "Picture 12"},
{"img": "http://www.mitxiong.com/NewsImages/2012081218248259 .jpg", "title": "Picture 13"},
{"img": "http://www.mitxiong.com/NewsImages/2012080621278799.jpg", "title": "Picture 14"},
{"img": "http://www.mitxiong.com/NewsImages/2012072907484455.jpg", "title": "Picture 15"},
{"img": "http://www .mitxiong.com/NewsImages/2012072521564314.jpg", "title": "Picture 16"},
{"img": "http://www.mitxiong.com/NewsImages/2012072507238259.jpg", "title ": "Picture 17"},
{"img": "http://www.mitxiong.com/NewsImages/2012072409035684.jpg", "title": "Picture 18"},
{"img ": "http://www.mitxiong.com/NewsImages/2012072219405236.jpg", "title": "Picture 19"},
{"img": "http://www.mitxiong.com/NewsImages /2012071218416980.jpg", "title": "Picture 20"}
]}');
?>