Detailed explanation of the use of $filter filter in AngularJS (custom filter)

1. Built-in filter

* $filter 过滤器，是angularJs中用来处理数据以更好的方式展示给我用户。比如格式化日期，转换大小写等等。
* 过滤器即有内置过滤器也支持自定义过滤器。内置过滤器很多，可以百度。关键是如何使用：
* 1.在HTML中直接使用内置过滤器
* 2.在js代码中使用内置过滤器
* 3.自定义过滤器
*
* （1）常用内置过滤器
*    number 数字过滤器，可以设置保留数字小数点后几位等
*    date  时间格式化过滤器，可自己设置时间格式
*    filter 过滤的数据一般是数组，数组中的数据可以是对象，字符串等
*    orderBy 排序根据数组中某一个元素的属性排序等
*    lowercase 转换小写
*    uppercase 转换大写
*    limitTo  字符串剪切 使用格式{{被剪切的字符串|limitTo：数值}} 数值绝对值代表要切得字符个数，正代表从头开始切，负值相反。
*
* */

2. Custom filter

/*
* 定义格式：
* 模块名称.filter(‘过滤器名字'，function(){
*    return function(被过滤数据，条件1，条件2.。。。){
*    //过滤操作
*    }
* });
* */

Apply the above format to define two simple custom filters Define one filter with conditions and one without conditions.

(1) [Without conditions], function: fixed conversion (sometimes you will encounter role codes, store codes, etc. in the project, but when displayed, the corresponding Chinese must be displayed, such as field code: 101 represents Boss

At this time, there are more code values ​​like this, so it is better to use a filter)

myApp.filter("ChangeCode",function () {
  return function (inputData) {
    var changed = "";
    switch (inputData){
      case '101':changed = "老板";break;
      case '102':changed = "经理";break;
      case '103':changed = "员工";break;
    }
    return changed;
  }
});
/*完成，说一下使用场景（就这个过滤器的功能）和方式。
* 场景：服务器返回的数据中有个字段code，直接放标签里<div>{{data.code}}</div>,会显示code值而不是code值对应的职称，这时候就可以用这个专门
*    针对这个转换的自定义过滤器
* 使用方式：
*      （1）HTML中：<div>{{data.code | ChangeCode}}</div>//跟内置过滤器一样的方式
*      （2）js中：变量 = $filter("ChangeCode")(被过滤的code数据)//一样的调用方式
*     
* */

(2) [With conditions], the function filters out. A set of data whose field value is a certain value in an array. For example, here is a filter that filters out all ages that are a certain value. The parameter is age

myApp.filter("deleteByAge",function () {
  return function (input,byAge,age) {
    var array = [];
    for(var i=0;i<input.length;i++){
      if(input[i][byAge]!=age){
        array.push(input[i]);
      }
    }
    return array;
  }
})
/*
* 处理一组数据的时候一般很少用在HTML当中，带条件的自定义过滤器是根据年龄值，也可以根据数组元素中的任意一个属性值进行删除过滤。
* 使用方式：变量 = $filter("deleteByAge")(数组，“属性名称”，属性值)；
* */

[Summary of how to use built-in filters]

(1) The general format in HTML is: {{Filtered data | Filter Name: Condition 1: Condition 2.. . . }} ; Filter conditions are separated by ':'.

(2) The general format in the code is: Variable = $filter("filter name") (filtered data, filter condition 1, Filter condition 2, . . . )

(1) Definition format: Module name

FilterName: Filter name

Parameter 1: Filtered data

Parameter 2: Generally filter conditions, there can be multiple, the following parameter 3 always It is all up to parameter N, add it as needed.

The above is the detailed explanation of the use of $filter filter (custom filter) in AngularJS introduced by the editor. I hope it will be helpful to you. If you have any questions, please leave me a message. Editor Will reply to everyone promptly. I would also like to thank you all for your support of the PHP Chinese website!

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