code: function countCharFromStr(str, ch) {
      let strArr = [...str];
      let count = 0;
      for (let k in strArr) {
          if (strArr[k] === ch) {
              count++
          }
      }
      return count
  }
docs: count specific character in string
  @param str target string
  @param ch specific character
  @returns {number} characters count