search javascript string and get word index instead of char

Question

I would like to search in javascript string and get all string occurrence by word index for example:

var str = 'Hello this is my this is world'
myFindWordIndex(str, 'this is') ==> [1, 4]

(two occurrences of the search string, one starts at word index 1 and one starts at index 4) the solution can use JQuery

How can you highlight words when you only know the word number. — , Jul 12 '16 at 20:28
@Mohammad your answer looks great, why don't you add it inline here? — Roi, Jul 12 '16 at 20:30
@sin, i already tagged all of my words with id= (w0, w1, w2....) — Roi, Jul 12 '16 at 20:33
Try to create an array of where the words start. Use something like this `/\b(?=\w)/`. Loop through that array testing each location for your target `this is`. The index is the word index. Or, you could do jumbo gyrations if you'd like. — , Jul 12 '16 at 20:33
@Roi Because it has problem for some word. See https://jsfiddle.net/kfnrwkk0/1/ — Mohammad, Jul 12 '16 at 20:34
@Mohammad, what problem does it have? (I already took it to my code) — Roi, Jul 12 '16 at 20:40
My code return extra index, for example if you check `is` word, it return `[2, 4, 7, 9]` but right array is `[2, 5]`. — Mohammad, Jul 13 '16 at 07:11

score 1 · Answer 1 · edited Jul 20 '16 at 21:28

I would split the phrase you're trying to find and where you're trying to find it into words. Then simply check if the phrase contains each piece of the search phrase.

function check(hay, needle, from) {
  var i = 1;
  while (i < needle.length) {
    if (hay[from] != needle[i])
      return false;
    i++;
    from++;
  }
  return true;
}

function myFindWordIndex(str, findme) {
  var indices = [];
  var needle = findme.split(" ");
  var hay = str.split(" ");

  for (var i = 0; i < hay.length - needle.length; i++) {
    if (hay[i] == needle[0] && (needle.length==1||check(hay, needle, i)))
      indices.push(i);
  }
  return indices;
}
var str = 'Hello this is my this is world';

console.log(myFindWordIndex(str, 'this is')); // ==> [1, 4]

score 0 · Answer 2 · edited May 23 '17 at 10:28

using function from How to find indices of all occurrences of one string in another in JavaScript? for multi search

function getIndicesOf(searchStr, str, caseSensitive) {
    var startIndex = 0, searchStrLen = searchStr.length;
    var index, indices = [];
    if (!caseSensitive) {
        str = str.toLowerCase();
        searchStr = searchStr.toLowerCase();
    }
    while ((index = str.indexOf(searchStr, startIndex)) > -1) {
        indices.push(index);
        startIndex = index + searchStrLen;
    }
    return indices;
}

function myFindWordIndex(str, search_str) {
    var res = [];
    $.each(getIndicesOf(search_str, str, true), function(i, v) {
        res.push(str.slice(0, v).split(' ').length)
    });
    return res;
}

It's not he it's me, anyway changed it to full solution – Roi Jul 12 '16 at 20:14 — Roi, Jul 12 '16 at 20:14

score 0 · Answer 3 · answered Jul 12 '16 at 20:15

0

Here's a clunky solution using Lodash.js.

function run(str, searchingFor) {
  return _.flatten(
    _.zip(str.split(/\s+/), str.split(/\s+/))
  )
  .slice(1, -1)
  .join(' ')
  .match(/\w+\s+\w+/g)
  .reduce((a, b, i) => {
    return b === searchingFor
      ? a.concat(i)
      : a;
  }, []);
}

Here is it running...

run('Hello this is my this is world', 'this is');
// => [1, 4]

Not ideal. Not very portable. But it works.

answered Jul 12 '16 at 20:15

wpcarro

1,528
10
13

It's a good answer but I prefer not to use more external packages – Roi Jul 12 '16 at 20:35

score 0 · Answer 4 · answered Jul 12 '16 at 20:53

adding @Mohammad's answer since it looks the cleanest:

var str = 'Hello this is my this is world'
var pos = myFindWordIndex(str, 'this is');
console.log(pos);

function myFindWordIndex(str, word){
    var arr = [];
    var wordLength = word.split(" ").length;
    var position = 0;
    str.split(word).slice(0, -1).forEach(function(value, i){
        position += value.trim().split(" ").length;
        position += i > 0 ? wordLength : 0;
        arr.push(position); 
    });
    return arr;
}

search javascript string and get word index instead of char

4 Answers4