d3plus-common/es/src/merge.js

import {merge, sum} from "d3-array";
import {keys} from "d3-collection";

/**
    @function merge
    @desc Combines an Array of Objects together and returns a new Object.
    @param {Array} objects The Array of objects to be merged together.
    @param {Object} aggs An object containing specific aggregation methods (functions) for each key type. By default, numbers are summed and strings are returned as an array of unique values.
    @example <caption>this</caption>
merge([
  {id: "foo", group: "A", value: 10, links: [1, 2]},
  {id: "bar", group: "A", value: 20, links: [1, 3]}
]);
    @example <caption>returns this</caption>
{id: ["bar", "foo"], group: "A", value: 30, links: [1, 2, 3]}
*/
function objectMerge(objects, aggs) {
  if ( aggs === void 0 ) aggs = {};


  var availableKeys = new Set(merge(objects.map(function (o) { return keys(o); }))),
        newObject = {};

  availableKeys.forEach(function (k) {
    var values = objects.map(function (o) { return o[k]; });
    var value;
    if (aggs[k]) { value = aggs[k](values); }
    else {
      var types = values.map(function (v) { return v || v === false ? v.constructor : v; }).filter(function (v) { return v !== void 0; });
      if (!types.length) { value = undefined; }
      else if (types.indexOf(Array) >= 0) {
        value = merge(values.map(function (v) { return v instanceof Array ? v : [v]; }));
        value = Array.from(new Set(value));
        if (value.length === 1) { value = value[0]; }
      }
      else if (types.indexOf(String) >= 0) {
        value = Array.from(new Set(values));
        if (value.length === 1) { value = value[0]; }
      }
      else if (types.indexOf(Number) >= 0) { value = sum(values); }
      else if (types.indexOf(Object) >= 0) { value = objectMerge(values.filter(function (v) { return v; })); }
      else {
        value = Array.from(new Set(values.filter(function (v) { return v !== void 0; })));
        if (value.length === 1) { value = value[0]; }
      }
    }
    newObject[k] = value;
  });

  return newObject;

}

export default objectMerge;

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