如何对从 AJAX 调用返回的数据进行分组？

Question

I created a list in sharepoint gathering user information. Each entry has date. Some days have many entries. My goal is to create a select menu that has the dates. When I click the menu the dates populate but they repeat. How do I return them as a single value?

I've tried to nest another for loop and an if statement.

$.ajax({
   url:url,
   method:'GET',
   headers:{ 'Accept': 'application/json; odata=verbose' },
   success: function(data){
     var dat = data.d.results;
      for (var i = 0;i < dat.length; i++){
    html+='<optionvalue='+itm.dateVal+'>'+itm.dateVal+'</option>';
       }     $('#week-selector').append(html);
   },
   error: function(e){
    console.log('error:'+e);
   }            
});

The output I am getting is:

3/3/2019
3/3/2019
3/3/2019
3/3/2019
3/6/2019
3/6/2019
3/10/2019
3/10/2019

The output I want to get is:

3/3/2019
3/6/2019
3/10/2019

Answer 1

You can easily write a filter function to get distinct values.

 var arr = [ "3/3/2019", "3/3/2019", "3/3/2019", "3/3/2019", "3/6/2019", "3/6/2019", "3/10/2019", "3/10/2019" ]; var distinctDates = arr.filter(function(val, idx, self){ return self.indexOf(val) === idx; }); console.log(distinctDates);

in ES6 you can do it the following way

 var arr = [ "3/3/2019", "3/3/2019", "3/3/2019", "3/3/2019", "3/6/2019", "3/6/2019", "3/10/2019", "3/10/2019" ]; var distinctDates = [...new Set(arr)]; console.log(distinctDates);

Answer 2

You can remove duplicate values using a Set and then converting it back to an array:

var arr = [
    "3/3/2019",
    "3/3/2019",
    "3/3/2019",
    "3/3/2019",
    "3/6/2019",
    "3/6/2019",
    "3/10/2019",
    "3/10/2019"
];

console.log(Array.from(new Set(arr)));
// ["3/3/2019", "3/6/2019", "3/10/2019"]```

Answer 3

var arr = ['3/3/2019', '3/3/2019', '4/4/2019']

arr.filter(function(item, i){ return arr.indexOf(item) == i;})