arrays - Loop Iteration avoid same indexes javascript -
i've scenario want walk in array in javascript, , checking if index matches option push or print once. ive 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 iterate array on every thing , if thing index matched previous leave else push in array. try tackle scenario using global variable setting wont help.
desired output:
[item1 ..... item7] var currentitem ; var myarr; (var j = 1; j <= 100; j++) { (var = 0; <= 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) } } }
given array arr:
["item1", "dummydata1", "dummydata2", "item2", ... ] the easiest way find set of members of form itemc, c constant mark placeholder array @ appropriate indices:
var getuniquesetofitems = function (arr) { // our placeholder array var p = []; // loop through every element in `arr` (var = 0; < arr.length; i++) { // if first 4 characters of `arr[i]` "item" if (arr[i].slice(0,4) == "item") // set our placeholder array @ index true p[i] = true; } // filter placeholder array indices marked true // map filtered array indices return p.filter(function (d) { return d; }).map(function (d, i) { return i; }); } this solution has benefit of having o(n) time complexity o(n) additional space. other easiest solution can think of (looping through array check whether next element there) slower, @ o(n^2).
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