Loop Iteration avoid same indexes javascript

Question

I've a scenario that I want to walk in array in javascript, and checking that if the index matches with any option then just PUSH this or print this once. Ive a following array:

["ITEM1", "dummyData1", "dummyData2", "ITEM2", "dummyData1", "dummyData2", "ITEM3", "dummyData1", "dummyData2", "ITEM4", "dummyData1", "dummyData2", "ITEM4", "dummyData1", "dummyData2", "ITEM4", "dummyData1", "dummyData2", "ITEM4", "dummyData1", "dummyData2", "ITEM5", "dummyData1", "dummyData2", "ITEM5", "dummyData1", "dummyData2", "ITEM6", "dummyData1", "dummyData2", "ITEM7", "dummyData1", "dummyData2", "ITEM7", "dummyData1", "dummyData2"]

I want to iterate this array on every THING and if THING index matched with the previous then leave this else push in the array. I try to tackle this scenario using the global variable setting but it wont help.

Desired Output:

[ITEM1 ..... ITEM7]




 var currentItem ;
var myArr;
for (var j = 1; j <= 100; j++) {

 for (var i = 0; i <= res[j].length-1; i++) {

 var option1 = (res[j][i].match(/THING1-/));
 var option2 = (res[j][i].match(/THING2-/));
 var option3 = (res[j][i].match(/THING3-/));
 var option4 = (res[j][i].match(/THING4-/));
 var item;
                            if (option1 != null)
                               item = "THE_THING-1";
                            else    if (option2 != null)
                                 item = "THE_THING-2";
                            else       if (option3 != null)
                                item= "THE_THING-3";
                            else           if (option4 != null)
                                 item = "THE_THING-4";
if (currentItem!= item)
{
currentItem = item;
myArr.push("THING"+j)
}
}
}

Please clarify exactly what you're trying to accomplish. As it stands, your question is not very clear. — royhowie, Apr 14 '15 at 19:02
I want to push all ITEM1 to ITEM7 for once .. remove reduncy of that — developer, Apr 14 '15 at 19:05
So you want to filter that array based on some condition? What is the condition? — royhowie, Apr 14 '15 at 19:07
the condition is, when "ITEM" keyword with a number, found in array, it pushes that but avaoid redundency — developer, Apr 14 '15 at 19:13

score 1 · Accepted Answer · answered Apr 14 '15 at 19:18

Given an array arr:

["ITEM1", "dummyData1", "dummyData2", "ITEM2", ... ]

The easiest way to find the set of all members of the form ITEMc, where c is a constant would be to mark a placeholder array at the appropriate indices:

var getUniqueSetOfItems = function (arr) {
    // our placeholder array
    var p = [];
    // loop through every element in `arr`
    for (var i = 0; i < arr.length; i++) {
        // if the first four characters of `arr[i]` are "ITEM"
        if (arr[i].slice(0,4) == "ITEM")
            // then set our placeholder array at that index to true
            p[i] = true;
    }
    // filter the placeholder array for all indices marked true
    // then map the filtered array to its indices
    return p.filter(function (d) { return d; }).map(function (d, i) { return i; });
}

This solution has the benefit of having O(n) time complexity with only O(n) additional space. The other easiest solution I can think of (looping through the array to check whether the next element is already there) would be much slower, at O(n^2).

score 0 · Answer 2 · answered Apr 14 '15 at 19:17

Is this what you wish to do:

var array = [],
  data = ['dummydata1', 'dummydata2'],
  itemNameBasis = "ITEM";


for(var i = 1; i < 8; i++) {
   var currentItemName = itemNameBasis + i;
   // here you may change data for different items depending on the name
   if(array.indexOf(currentItemName) == -1) {
      array.push(currentItemName);
      array = array.concat(data);
   }
}

console.log(array);

score 0 · Answer 3 · edited May 23 '17 at 11:57

Try this:

// add a "i" at the end to make the regex case insensitive
// i.e.: /^ITEM\d+$/i
var regex = /^ITEM\d+$/;

var foundItems = {};
filteredItems = myArr.filter(function(item) {
    if(regex.test(item) && !foundItems.hasOwnProperty(item)) { 
        foundItems[item] = true;
        return true;
    }
    return false;
});

On IE the filter function is available only from IE9. If you need to support older versions of IE you'll need to iterate over the array.

The array unique elegant solution found at Unique values in an array.

Loop Iteration avoid same indexes javascript

3 Answers3