d3plus-common/es/src/assign.js

Common functions and methods used across D3plus modules.

import {default as isObject} from "./isObject";

/**
    @function assign
    @desc A deeply recursive version of `Object.assign`.
    @param {...Object} objects
    @example <caption>this</caption>
assign({id: "foo", deep: {group: "A"}}, {id: "bar", deep: {value: 20}}));
    @example <caption>returns this</caption>
{id: "bar", deep: {group: "A", value: 20}}
*/
function assign() {
  var objects = [], len = arguments.length;
  while ( len-- ) objects[ len ] = arguments[ len ];


  var target = objects[0];
  var loop = function ( i ) {

    var source = objects[i];

    Object.keys(source).forEach(function (prop) {

      var value = source[prop];

      if (isObject(value)) {
        if (target.hasOwnProperty(prop) && isObject(target[prop])) { target[prop] = assign({}, target[prop], value); }
        else { target[prop] = assign({}, value); }
      }
      else if (Array.isArray(value)) {

        if (target.hasOwnProperty(prop) && Array.isArray(target[prop])) {

          var targetArray = target[prop];

          value.forEach(function (sourceItem, itemIndex) {

            if (itemIndex < targetArray.length) {
              var targetItem = targetArray[itemIndex];

              if (Object.is(targetItem, sourceItem)) { return; }

              if (isObject(targetItem) && isObject(sourceItem) || Array.isArray(targetItem) && Array.isArray(sourceItem)) {
                targetArray[itemIndex] = assign({}, targetItem, sourceItem);
              }
              else { targetArray[itemIndex] = sourceItem; }

            }
            else { targetArray.push(sourceItem); }

          });
        }
        else { target[prop] = value; }

      }
      else { target[prop] = value; }

    });
  };

  for (var i = 1; i < objects.length; i++) loop( i );

  return target;

}

export default assign;

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