util.js

const dateUtil = require('fecha');

export function merge(target) {
  for (var i = 1, j = arguments.length; i < j; i++) {
    var source = arguments[i];
    for (var prop in source) {
      if (source.hasOwnProperty(prop)) {
        var value = source[prop];
        if (value !== undefined) {
          target[prop] = value;
        }
      }
    }
  }

  return target;
}

export function formatDate(date, format) {
  if (!(date instanceof Date)) return '';
  return dateUtil.format(date, format || 'YYYY-MM-DD');
}

export function parseDate(string, format) {
  return dateUtil.parse(string, format || 'YYYY-MM-DD');
}

export function debounce(fn, delay) {
  var timer;

  return function() {
    var context = this;
    var args = arguments;
    if (timer) {
      clearTimeout(timer);
      timer = null;
    }
    timer = setTimeout(function() {
      fn.apply(context, args);
      timer = null;
    }, delay);
  };
}

export function throttle(fn, delay) {
  var now, lastExec, timer, context, args;

  var execute = function() {
    fn.apply(context, args);
    lastExec = now;
  };

  return function() {
    context = this;
    args = arguments;

    now = Date.now();

    if (timer) {
      clearTimeout(timer);
      timer = null;
    }

    if (!lastExec) {
      execute();
    } else {
      var diff = delay - (now - lastExec);
      if (diff < 0) {
        execute();
      } else {
        timer = setTimeout(function() {
          execute();
        }, diff);
      }
    }
  };
}

export function getNestedPath(object, nestedProp) {
  let propertyArr = nestedProp.split('.');
  let property = propertyArr.pop();
  return getPath(object, propertyArr.join('.')).fields[property];
}

export function getPath(object, prop) {
  prop = prop || '';
  var paths = prop.split('.');
  var current = object;
  var result = null;
  for (var i = 0, j = paths.length; i < j; i++) {
    var path = paths[i];
    if (!current) break;

    if (i === j - 1) {
      result = current[path];
      break;
    }
    current = current[path];
  }
  return result;
}

export function setPath(object, prop, value) {
  if (prop === undefined || prop === null) return;

  if (typeof prop === 'object') {
    var target = prop;
    for (prop in target) {
      if (target.hasOwnProperty(prop)) {
        setPath(object, prop, target[prop]);
      }
    }
  } else {
    prop = prop || '';
    var paths = prop.split('.');
    var current = object;
    for (var i = 0, j = paths.length; i < j; i++) {
      var path = paths[i];
      if (!current) break;
      if (i === j - 1) {
        current[path] = value;
        break;
      }
      current = current[path];
    }
  }
}

var scrollbarWidth;

export function getScrollbarWidth() {
  if (scrollbarWidth !== undefined) return scrollbarWidth;

  var outer = document.createElement('div');
  outer.style.visibility = 'hidden';
  outer.style.width = '100px';
  outer.style.position = 'absolute';
  outer.style.top = '-9999px';
  document.body.appendChild(outer);

  var widthNoScroll = outer.offsetWidth;
  outer.style.overflow = 'scroll';

  var inner = document.createElement('div');
  inner.style.width = '100%';
  outer.appendChild(inner);

  var widthWithScroll = inner.offsetWidth;
  outer.parentNode.removeChild(outer);

  return widthNoScroll - widthWithScroll;
}