hd-utils/lib/utils/string/occurrencesCount.js

A handy utils for modern JS developers

/** Function that count occurrences count of a substring in a string;
 * @param {String} string               The string
 * @param {String} subString            The sub string to search for
 * @param {Boolean} [allowOverlapping]  Optional. (Default:false)
 *
 * @example `
 * occurrencesCount("foofoofoo", "bar"); //0

   occurrencesCount("foofoofoo", "foo"); //3

   occurrencesCount("foofoofoo", "foofoo"); //1

   //allowOverlapping:true
   occurrencesCount("foofoofoo", "foofoo", true); //2
    foofoofoo
  1`----´
    2  `----´

 * `
 *
 * @author Vitim.us https://gist.github.com/victornpb/7736865
 * @see Unit Test https://jsfiddle.net/Victornpb/5axuh96u/
 * @see https://stackoverflow.com/a/7924240/938822
 */
export default function occurrencesCount(string, subString, allowOverlapping) {
    string += '';
    subString += '';
    if (subString.length <= 0)
        return string.length + 1;
    let n = 0;
    let pos = 0;
    let step = allowOverlapping ? 1 : subString.length;
    while (true) {
        pos = string.indexOf(subString, pos);
        if (pos >= 0) {
            ++n;
            pos += step;
        }
        else
            break;
    }
    return n;
}