Angular phone number filter

phone-filter.js

/**
 * [Filter] phone number filter
 * Usage: {{ phoneNumber | {prefix} {range} {range} {range} }}
 * {prefix} - e.g. {+48}
 * {range} - e.g. {3} or {2-3}
 *     -> where first number in {2-3} defines slicing when string.length equals 7, 
 *       second defines slicing for length equal 9
 */
angular.module('app').filter('phoneNumber', function() {
  return function(item, pattern) {

    // if no item return empty string
    if (!item) {
      return '';
    }

    // if not pattern provided set default pattern
    if (!pattern) {
      pattern = '{+48} {3} {2-3} {2-3}';
    }

    try {
      if (pattern) { 
        pattern.match(/\{(\S{1,3})\}/g);
      }
    } catch (err) {
      throw new Error('Please enter proper filter pattern. For example: {+48} {3} {2-3} {2-3}');
    }

    // get patterns
    var patternArray = pattern.match(/\{(\S{1,3})\}/g);

    // get prefix and gap
    var prefix = patternArray[0].match(/\+\d{2}/);
    var gap = pattern.match(/}(\S|\s){/)[1];

    var formattedNumber = '';
    var phone = '';

    // slices length container
    var slices = [];

    var sliceRange = 0;
    var i;

    // clear filtered item from whitespaces
    item = item.toString().replace(new RegExp('^\\' + prefix + '|\\s+|', 'g'), '');

    // push slices to array from patternArray
    for (i = (prefix) ? 1 : 0; i < patternArray.length; i++) {
      if (patternArray[i].match(/[a-z]+/g)) {
        throw new Error('Please provide number range into filter');
      }

      if (patternArray[i].match(/\d/g).length === 1) {
        slices.push(patternArray[i].match(/\d/g)[0]);
      } else {
        slices.push(patternArray[i].match(/\d/g));
      }
    }

    // set slice range according to item.length
    switch (item.length) {
      case 9:
        sliceRange = 1;
        break;
      case 7:
        sliceRange = 0;
        break;
      default:
        return item;
    }

    // build phone number
    for (i = 0; i < slices.length; i++) {

      // if slice is not range type,
      // for example: {3}
      if (typeof slices[i] !== 'object') {
        if (i === 0) {
          phone += item.slice(0, parseInt(slices[i], 10)) + gap;
        } else {
          if (i !== (slices.length - 1)) {
            phone += item.slice( ((phone.length) - (gap.length * i)), ((phone.length) - (gap.length * i)) + parseInt(slices[i], 10)) + gap;
          } else {
            phone += item.slice( ((phone.length) - (gap.length * i)), ((phone.length) - (gap.length * i)) + parseInt(slices[i], 10));
          }
        }

      // if slices is range type,
      // for example {2-3}
      } else {
        if (i === 0) {
          phone += item.slice(0, parseInt(slices[i][sliceRange], 10)) + gap;
        } else {
          if (i !== (slices.length - 1)) {
            phone += item.slice( ((phone.length) - (gap.length * i)), ((phone.length) - (gap.length * i)) + parseInt(slices[i][sliceRange], 10)) + gap;
          } else {
            phone += item.slice( ((phone.length) - (gap.length * i)), ((phone.length) - (gap.length * i)) + parseInt(slices[i][sliceRange], 10))
          }
        }
      }
    }

    // if prefix is defined add prefix to number
    if (prefix) {
      formattedNumber = prefix + gap + phone;
    } else {
      formattedNumber = phone;
    }

    return formattedNumber;
  };
});