javascript常用工具関数のまとめ

  /**
   *  url    
   * @return {object}
   * @example
   * getRequest()  getRequest().paramA
   */
function getRequest() {
    var searchString = window.location.search.substring(1),
        params = searchString.split("&"),
        hash = {};
    if (searchString == "") return {};
    for (var i = 0; i < params.length; i++) {
        var pos = params[i].indexOf('=');
        if (pos == -1) { continue; }
        var paraName = params[i].substring(0, pos),
            paraValue = params[i].substring(pos + 1);
        hash[paraName] = paraValue;
    }
    return hash;
}

  /**
   *   url  
   * @param {string} url url  
   * @param {string|object} key       
   * @param {string} value  
   * @return {string}     url
   * @example
   * appendQuery('lechebang.com', 'id', 3);
   * appendQuery('lechebang.com?key=value', { cityId: 2, cityName: '  '});
   */
  function appendQuery (url, key, value) {
    var options = key;
    if (typeof options == 'string') {
      options = {};
      options[key] = value;
    }
    options = $.param(options);
    if (url.includes('?')) {
      url += '&' + options
    } else {
      url += '?' + options
    }
    return url;
  }

  /**
   *             
   * @param {Date, Date}  date1 date2
   * @return {object | null} 
   * @example
   * getDiff(new Date('2017-09-08'), new Date())
   */
function getDiff(date1, date2) {
     if (!date1.getTime || !date2.getTime) return null
     var ms = (date1.getTime() - date2.getTime());
     var day1 = Math.round(ms / 24 / 3600 / 1000),
         hh1 = Math.round((ms / 3600 / 1000) % 24),
         mm1 = Math.round((ms / 1000 / 60) % 60),
         ss1 = Math.round((ms / 1000) % 60);
     return {
         day: day1,
         hour: hh1,
         minute: mm1,
         second: ss1
      };
}

  /**
   *  canvas   image  
   * @param {string}  cId
   * @return {object HTMLImageElement} 
   * @example
   * canvasToImg('canvas')  canvasToImg('#canvarsId')
   */
function canvasToImg(cId){
    let canvas = document.querySelector(cId)
    if (!canvas || !canvas.toDataURL) return new Image()
    let imgData = canvas.toDataURL('image/png'),
        imgs= new Image();
        imgs.src=imgData;
    return imgs
}

  /**
   *        guid
   * @return {string}
   * @example
   * // 7f603b20-17ff-4f47-aeb9-e7996de04939
   * util.guid();
   * @see http://stackoverflow.com/questions/105034/create-guid-uuid-in-javascript
   */
  function guid () {
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
      var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
      return v.toString(16);
    });
  }

  function isLeapYear (year) {
    if (year % 100 === 0) {
      if (year % 400 === 0) {
        return true;
      }
    } else if (year % 4 === 0) {
      return true;
    }
    return false;
  }
  /**
   *           
   * @return {number}
   * @param {string | number}  year month
   * @example
   * getDaysInMonth(2017, 9)
   */
  function getDaysInMonth (year, month) {
    return [31, isLeapYear(year) ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31][month];
  }

  /**
   *              
   * @param{object, array} obj key
   * @return{object}
   * @example
   * pick(obj, [key1, key2])
   */
  function pick (obj, keys) {
    let result = {}
    if (!obj || !keys.forEach) {
      return result
    }
    keys.forEach((item) => {
      if (obj.hasOwnProperty(item)) {
        result[item] = obj[item]
      }
    })
    return result
  }

  /**
   *                
   * @param{object} obj 
   * @return{object}
   * @example
   * isObject (null) isObject (() => {} )
   */
function isObject (obj) {
    var type = typeof obj;
    return type === 'function' || type === 'object' && !!obj;
  }

  /**
   *                   
   * @param{function} Ctor 
   * @return{boolean}
   * @example
   * isNative (window.Symbol)  isNative (window.Promise)
   */
function isNative (Ctor) {
  return typeof Ctor === 'function' && /native code/.test(Ctor.toString())
}

  /**
   *                   
   * @param{object} obj 
   * @return{object}
   * @example
   * cloneDeep(obj)
   */
  function cloneDeep (obj) {
    if (!isObject(obj)) return obj;
    let result
    if (Array.isArray(obj)) {
      result = []
      obj.forEach((item) => {
        result.push(cloneDeep(item))
      })
      return result
    }
    result = {}
    for (let key in obj) {
      let item = obj[key]
      if (_.isObject(item)) {
        result[key] = cloneDeep(item)
      } else {
        result[key] = item
      }
    }

    return result
  }

/**
   *            ,     ，  ，       
   * @return {null|number}      ，      ，  null
   * @example
   * getDistance(31.282055633974, 121.379623888259)
   */
  function getDistance (endLat, endLon, startLat, startLon) {
    if (!startLat) {
      let address = Lizard.state.address

      if (address && address.lat) {
        startLat = address.lat
        startLon = address.lon
      }
    }

    //     
    if (!startLat) {
      return null
    }

    const PI = Math.PI
    let lon1 = (PI / 180) * startLon
    let lon2 = (PI / 180) * endLon 
    let lat1 = (PI / 180) * startLat  
    let lat2 = (PI / 180) * endLat 
    //       
    let R = 6378.137;  

    //       km，       ，  *1000      
    let d = Math.acos(Math.sin(lat1) * Math.sin(lat2) + Math.cos(lat1) * Math.cos(lat2) * Math.cos(lon2 - lon1)) * R;  

    return parseInt(d * 1000, 10)
  }

/**
   *     url，    promise  ，     resolve
   * @return {Promise} 
   * @example
   * loadImg(url).then(console.log('    ')).catch(err => {console.log(err)})
   */
  function loadImg (url) {
    return new Promise((resolve, reject) => {
      let img = new Image()

      img.addEventListener('load', function() {
        resolve([img.width, img.height])
      }, false)

      img.addEventListener('error', reject, false)

      img.src = url
    })
  }

/**
   *      ，     ，       
   * @return {string} 
   * @param{string, number} str n 
   * @example
   * loadImg(url).then(console.log('    ')).catch(err => {console.log(err)})
   */
  const repeat = (str, n) => {
    let res = ''
    while (n) {
      if (n % 2 === 1) res += str
      if (n > 1) str += str
      n >>= 1
    }
    return res
  }

/**
   *      ，     '$'  '_'  
   * @return {Boolean} 
   * @param{string} str
   * @example
   * isReserved (‘$’)  isReserved (‘param’)
   */
function isReserved (str) {
  var c = (str + '').charCodeAt(0);
  return c === 0x24 || c === 0x5F
}

/**
   *    promise       finally，      ，    promise             
   * @param{function} callback
   * @example
   *  server.listen(0).then(function () { // run test }).finally(server.stop);
   */
Promise.prototype.finally = function (callback) {
  let P = this.constructor;
  return this.then(
    value  => P.resolve(callback()).then(() => value).catch(e => {console.error(e)}),
    reason => P.resolve(callback()).then(() => { throw reason }).catch(e => {console.error(e)})
  );
};

/**
   *        dom              
   *         false   ， true                true
   * @param {object，Boolean}
   * @example
   *  elementIsVisibleInViewport(document.querySelector('div'), true)
   */
const elementIsVisibleInViewport = (el, partiallyVisible = false) => {
  const { top, left, bottom, right } = el.getBoundingClientRect();
  const { innerHeight, innerWidth } = window;
  return partiallyVisible
    ? ((top > 0 && top < innerHeight) || (bottom > 0 && bottom < innerHeight)) &&
        ((left > 0 && left < innerWidth) || (right > 0 && right < innerWidth))
    : top >= 0 && left >= 0 && bottom <= innerHeight && right <= innerWidth;
};