read-time-estimate/dist/read-time-estimate.cjs.js

A Medium like read time estimate with more accuracy and customisable values

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

/* https://help.medium.com/hc/en-us/articles/214991667-Read-time */

/* https://blog.medium.com/read-time-and-you-bc2048ab620c */
const WORDS_PER_MIN = 275; // wpm

const IMAGE_READ_TIME = 12; // in seconds

const CHINESE_KOREAN_READ_TIME = 500; // cpm

const IMAGE_TAGS = ['img', 'Image'];

/**
 *  String#imageReadTime() -> { time, count }
 *
 *  Get Image Read Time from a string.
 *
 * */

function imageCount(imageTags, string) {
  const combinedImageTags = imageTags.join('|');
  const pattern = `<(${combinedImageTags})([\\w\\W]+?)[\\/]?>`;
  const reg = new RegExp(pattern, 'g');
  return (string.match(reg) || []).length;
}

function imageReadTime(customImageTime = IMAGE_READ_TIME, tags = IMAGE_TAGS, string) {
  let seconds = 0;
  const count = imageCount(tags, string);

  if (count > 10) {
    seconds = count / 2 * (customImageTime + 3) + (count - 10) * 3; // n/2(a+b) + 3 sec/image
  } else {
    seconds = count / 2 * (2 * customImageTime + (1 - count)); // n/2[2a+(n-1)d]
  }

  return {
    time: seconds / 60,
    count
  };
}

/**
 *  String#wordsReadTime() -> { characterTime, otherLanguageTime, wordTime, wordCount }
 *
 *  Get Words count from a string.
 *
 * */

function wordsCount(string) {
  const pattern = '\\w+';
  const reg = new RegExp(pattern, 'g');
  return (string.match(reg) || []).length;
} // Chinese / Japanese / Korean


function otherLanguageReadTime(string) {
  const pattern = '[\u3040-\u30ff\u3400-\u4dbf\u4e00-\u9fff\uf900-\ufaff\uff66-\uff9f]';
  const reg = new RegExp(pattern, 'g');
  const count = (string.match(reg) || []).length;
  const time = count / CHINESE_KOREAN_READ_TIME;
  const formattedString = string.replace(reg, '');
  return {
    count,
    time,
    formattedString
  };
}

function wordsReadTime(string, wordsPerMin = WORDS_PER_MIN) {
  const {
    count: characterCount,
    time: otherLanguageTime,
    formattedString
  } = otherLanguageReadTime(string);
  const wordCount = wordsCount(formattedString);
  const wordTime = wordCount / wordsPerMin;
  return {
    characterCount,
    otherLanguageTime,
    wordTime,
    wordCount
  };
}

/**
 *  String#stripTags() -> String
 *
 *  Strip HTML tags string.
 *
 * */
function stripTags(string) {
  const pattern = '<\\w+(\\s+("[^"]*"|\\\'[^\\\']*\'|[^>])+)?>|<\\/\\w+>';
  const reg = new RegExp(pattern, 'gi');
  return string.replace(reg, '');
}

/**
 *  String#stripWhitespace() -> String
 *
 *  Strip HTML tags string.
 *
 * */
function stripWhitespace(string) {
  return string.replace(/^\s+/, '').replace(/\s+$/, '');
}

/**
 *  String#humanizeTime() -> String
 *
 *  Convert time(in minutes) to a humanized string.
 *
 * */
function humanizeTime(time) {
  if (time < 0.5) {
    return 'less than a minute';
  }

  if (time >= 0.5 && time < 1.5) {
    return '1 minute';
  }

  return `${Math.ceil(time)} minutes`;
}

function readTime(string, customWordTime, customImageTime, chineseKoreanReadTime, imageTags) {
  const {
    time: imageTime,
    count: imageCount$$1
  } = imageReadTime(customImageTime, imageTags, string);
  const strippedString = stripTags(stripWhitespace(string));
  const {
    characterCount,
    otherLanguageTime,
    wordTime,
    wordCount
  } = wordsReadTime(strippedString, customWordTime);
  return {
    humanizedDuration: humanizeTime(imageTime + wordTime),
    duration: imageTime + wordTime,
    totalWords: wordCount,
    wordTime,
    totalImages: imageCount$$1,
    imageTime,
    otherLanguageTimeCharacters: characterCount,
    otherLanguageTime
  };
}

exports.default = readTime;
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