push only unique elements in an array

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-上瘾入骨i
-上瘾入骨i 2021-01-19 14:25

I have array object(x) that stores json (key,value) objects. I need to make sure that x only takes json object with unique key. Below, example \'id\' is the key, so i don\'t

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  • 2021-01-19 14:44

    would this accomplish what you're looking for? https://jsfiddle.net/gukv9arj/3/

    x = [
        {"id":"item1","val":"Items"},
        {"id":"item1","val":"Items"},
        {"id":"item2","val":"Items"}
    ];    
    
    var clickId = [];
    var list = JSON.parse(x);
    $.each(list, function(index, value){
        if(clickId.indexOf(value.id) === -1){
            clickId.push(value.id);
        }
    });
    
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  • 2021-01-19 14:48

    This is late but I did something like the following:

    let MyArray = [];
    MyArray._PushAndRejectDuplicate = function(el) {
        if (this.indexOf(el) == -1) this.push(el)
        else return;
    } 
    
    MyArray._PushAndRejectDuplicate(1); // [1]
    MyArray._PushAndRejectDuplicate(2); // [1,2]
    MyArray._PushAndRejectDuplicate(1); // [1,2]
    
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  • 2021-01-19 14:49

    Create a very readable solution with lodash.

    x = _.unionBy(x, [new Item(clickId, obj)], 'id');

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  • 2021-01-19 15:01

    JS objects are great tools to use for tracking unique items. If you start with an empty object, you can incrementally add keys/values. If the object already has a key for a given item, you can set it to some known value that is use used to indicate a non-unique item.

    You could then loop over the object and push the unique items to an array.

    var itemsObj = {};
    var itemsList = [];
    x = [{"id":"item1","val":"foo"},
        {"id":"item2","val":"bar"},
        {"id":"item1","val":"baz"},
        {"id":"item1","val":"bez"}];
    
    for (var i = 0; i < x.length; i++) {
        var item = x[i];
        if (itemsObj[item.id]) {
            itemsObj[item.id] = "dupe";
        }
        else {
            itemsObj[item.id] = item;
        }
    }
    
    for (var myKey in itemsObj) {
        if (itemsObj[myKey] !== "dupe") {
            itemsList.push(itemsObj[myKey]);
        }
    }
    
    console.log(itemsList);
    

    See a working example here: https://jsbin.com/qucuso

    If you want a list of items that contain only the first instance of an id, you can do this:

    var itemsObj = {};
    var itemsList = [];
    x = [{"id":"item1","val":"foo"},
        {"id":"item2","val":"bar"},
        {"id":"item1","val":"baz"},
        {"id":"item1","val":"bez"}];
    
    for (var i = 0; i < x.length; i++) {
        var item = x[i];
        if (!itemsObj[item.id]) {
            itemsObj[item.id] = item;
            itemsList.push(item);
        }
    }
    
    console.log(itemsList);
    
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  • 2021-01-19 15:04

    This is how I would do it in pure javascript.

    var x = [{"id":"item1","val":"Items"},{"id":"item1","val":"Items"},{"id":"item1","val":"Items"}];
    
    function unique(arr, comparator) {
      var uniqueArr = [];
      for (var i in arr) {
        var found = false;
        for (var j in uniqueArr) {
          if (comparator instanceof Function) {
            if (comparator.call(null, arr[i], uniqueArr[j])) {
              found = true;
              break;
            }
          } else {
            if (arr[i] == uniqueArr[j]) {
              found = true;
              break;
            }
          }
        }
        if (!found) {
          uniqueArr.push(arr[i]);
        }
      }
      return uniqueArr;
    };
    
    u = unique(x, function(a,b){ return a.id == b.id; });
    console.log(u);
    
    y = [ 1,1,2,3,4,5,5,6,1];
    console.log(unique(y));

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  • 2021-01-19 15:07

    You can't use inArray() because you are searching for an object.

    I'd recommend rewriting a custom find using Array.some() as follows.

    var x = [{"id":"item1","val":"Items"},{"id":"item1","val":"Items"},{"id":"item1","val":"Items"}]    
    
    var clickId = "item1";
    var found = x.some(function(value) {
      return value.id === clickId;
    });
    alert(found);

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