finding the word at a position in javascript

Question

For string input of 'this is a sentence' it must return 'is' when position is 6 or 7. When position is 0, 1, 2, 3 or 4 result must be 'this'.

What is the easiest way?

Answer 1

function getWordAt (str, pos) {

    // Perform type conversions.
    str = String(str);
    pos = Number(pos) >>> 0;

    // Search for the word's beginning and end.
    var left = str.slice(0, pos + 1).search(/\S+$/),
        right = str.slice(pos).search(/\s/);

    // The last word in the string is a special case.
    if (right < 0) {
        return str.slice(left);
    }

    // Return the word, using the located bounds to extract it from the string.
    return str.slice(left, right + pos);

}

This function accepts any whitespace character as a word separator, including spaces, tabs, and newlines. Essentially, it looks:

• For the beginning of the word, matched by /\S+$/
• Just past the end of the word, using /\s/

As written, the function will return "" if the index of a whitespace character is given; spaces are not part of words themselves. If you want the function to instead return the preceding word, change /\S+$/ to /\S+\s*/.

---

Here is some example output for "This is a sentence."

0: This
1: This
2: This
3: This
4:
5: is
6: is
7:
8: a
9:
10: sentence.
// ...
18: sentence.

---

Modified to return the preceding word, the output becomes:

0: This
1: This
2: This
3: This
4: This
5: is
6: is
7: is
8: a
9: a
10: sentence.
// ...
18: sentence.