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How to use the reduce function from lodash

Find comprehensive JavaScript lodash.reduce code examples handpicked from public code repositorys.

lodash.reduce is a JavaScript function that iterates over elements of a collection and returns a single value by performing an operation on each element.

packExternalModules.js

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  encoding: 'utf8'
}, (err, stdout, stderr) => {
  if (err) {
    // Only exit with an error if we have critical npm errors for 2nd level inside
    const errors = _.split(stderr, '\n');
    const failed = _.reduce(errors, (failed, error) => {
      if (failed) {
        return true;
      }
      return !_.isEmpty(error) && !_.some(ignoredNpmErrors, ignoredError => _.startsWith(error, `npm ERR! ${ignoredError.npmError}`));

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astrobench.js

GitHub: Irrelon/ForerunnerDB

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* @param {*} [accumulator] Initial value of the accumulator.
* @param {*} [thisArg] The `this` binding of `callback`.
* @returns {*} Returns the accumulated value.
* @example
*
* var sum = _.reduce([1, 2, 3], function(sum, num) {
*   return sum + num;
* });
* // => 6
*

711

+ 3 other calls in file

How does lodash.reduce work?

lodash.reduce takes three arguments: the collection to iterate over, a function that defines the operation to perform on each element, and an optional initial value.

The function is called for each element in the collection, passing in four arguments: the accumulated value (or the initial value, if provided), the current element, the index of the current element, and the entire collection. The function then returns the updated accumulated value.

If an initial value is provided, the first call to the function will use it as the accumulated value. If no initial value is provided, the first call to the function will use the first element of the collection as the accumulated value.

After all elements have been processed, the final accumulated value is returned.

i18n.cjs

GitHub: plone/volto

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 * Get messages from separate JSON files
 * @function getMessages
 * @return {Object} Object with messages
 */
function getMessages() {
  return reduce(
    concat(
      {},
      ...map(
        // We ignore the existing customized shadowed components ones, since most

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lodash-contrib.commonjs.js

GitHub: node4good/lodash-contrib

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module.exports.range               = _.range;
module.exports.rangeRight          = _.rangeRight;
module.exports.rcurry2             = _.rcurry2;
module.exports.rcurry3             = _.rcurry3;
module.exports.rearg               = _.rearg;
module.exports.reduce              = _.reduce;
module.exports.reduceRight         = _.reduceRight;
module.exports.reductions          = _.reductions;
module.exports.reject              = _.reject;
module.exports.remove              = _.remove;

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+ 92 other calls in file

Ai Example

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const _ = require("lodash");

const numbers = [1, 2, 3, 4, 5];
const sum = _.reduce(
  numbers,
  (accumulator, current) => accumulator + current,
  0
);

console.log(sum); // Output: 15

In this example, _.reduce() is called with the array numbers as the first argument, a function that adds the current element to the accumulated value as the second argument, and 0 as the third argument, which specifies that the initial value of the accumulator should be 0. The resulting sum of all elements in the array is stored in the sum variable, which is then printed to the console.

index.js

GitHub: adogor/npm-autolink

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dependencyTree,
(res, projectConf, projectName) => {
  const linkList = fileContent.link[projectName];
  if (linkList && projectConf.dependencies) {
    // If we have a linkList for this project && it has dependencies
    const toLinkInProject = _.reduce(
      projectConf.dependencies,
      (res2, depConf, depName) => {
        fileContent.link;
        if (linkList.includes(depName)) {

+ 11 other calls in file

contentful.js

GitHub: nsbarsukov/ml-bug-detector

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  var Type = parseableResourceTypes[resource.sys.type];
  return Type.parse(resource);
}


function stringifyArrayValues(object) {
  return _.reduce(object, function(object, value, key) {
    object[key] = _.isArray(value) ? value.join(',') : value;
    return object;
  }, {});
}

+ 530 other calls in file

lodash.js

GitHub: mdmarufsarker/lodash

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console.log(orderBy); // => ['c', 'a', 'b']


const partition = _.partition([1, 2, 3], n => n % 2);
console.log(partition); // => [[1, 3], [2]]


const reduce = _.reduce([1, 2], (sum, n) => sum + n, 0);
console.log(reduce); // => 3


const reduceRight = _.reduceRight([1, 2], (sum, n) => sum + n, 0);
console.log(reduceRight); // => 3

+ 15 other calls in file

wObjectHelper.js

GitHub: Waiviogit/waivio-api

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  }
  acc[el.name] = [el];
  return acc;
}, {});

return _.reduce(fieldTypes, (acc, el, index) => {
  const fieldLanguage = _.find(fieldsLanguages, (l) => l.type === index);
  const existedLanguages = _.get(fieldLanguage, 'languages', []);

  const nativeLang = _.filter(

+ 17 other calls in file

wObjectHelper.js

GitHub: Waiviogit/waivio-api

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    },
    'status.title': { $nin: REMOVE_OBJ_STATUSES },
  },
});

const options = _.reduce(wobjects, (acc, el) => {
  el.fields = addDataToFields({
    isOwnershipObj: !!ownership.length,
    fields: _.compact(el.fields),
    filter,

+ 5 other calls in file

schema-routes.js

GitHub: acacode/swagger-typescript-api

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const pathParamMatches = (routeName || "").match(
  /({(([a-zA-Z]-?_?\.?){1,})([0-9]{1,})?})|(:(([a-zA-Z]-?_?\.?){1,})([0-9]{1,})?:?)/g,
);

// used in case when path parameters is not declared in requestInfo.parameters ("in": "path")
const pathParams = _.reduce(
  pathParamMatches,
  (pathParams, match) => {
    const paramName = _.replace(match, /\{|\}|\:/g, "");

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+ 7 other calls in file

index.js

GitHub: sergeyksv/tinelic

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	});


	this.name = 'ValidationError';
	this.message = es;
	this.subject = 'Invalid Data';
	this.data = _.reduce(invalid.errors, function (m, f) {
		m.push(_.pick(f, ['property', 'message']));
		return m;
	},[]);
};

manager.js

GitHub: pocketnetteam/pocketnet.gui

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    return nodes

}

self.totalpending = function(){
    return _.reduce(self.initednodes(), function(r, node){
        return r + node.statistic.pending()
    }, 0)
}

+ 7 other calls in file

jsHarmony.LoadModels.js

GitHub: apHarmony/jsharmony

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var field_names = {};
_.each(model.fields, function(field){ field_names[field.name] = 1; });
for(var display_layout_name in model.display_layouts){
  var display_layout = model.display_layouts[display_layout_name];
  var column_names = {};
  display_layout.columns = _.reduce(display_layout['columns'],function(rslt,column){
    if(_.isString(column)){
      let column_name = column;
      if(!(column_name in field_names)){ _this.LogInit_ERROR('Display layout column not found: '+model.id+'::'+display_layout_name+'::'+column_name); return rslt; }
      if(column_name in column_names){ _this.LogInit_ERROR('Duplicate display layout column: '+model.id+'::'+display_layout_name+'::'+column_name); return rslt; }

index.js

GitHub: sluukkonen/iiris

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  const lodashCallback = (a, b) => a + b
  const ramdaCallback = (a, b) => a + b
  const nativeCallback = (a, b) => a + b
  return {
    iiris: () => A.reduce(iirisCallback, 0, array),
    lodash: () => _.reduce(array, lodashCallback, 0),
    ramda: () => R.reduce(ramdaCallback, 0, array),
    native: () => array.reduce(nativeCallback, 0),
  }
},

extend.js

GitHub: inPact/utils

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 * Projects the values of each key in object by running them through projector.
 * @param object - the object whose values to project
 * @param valueProjector - a function that receives a value and returns the projected result.
 */
mapObject(object, valueProjector) {
    return _.reduce(object, (res, val, key) => {
        res[key] = valueProjector(val, key, object);
        return res
    }, {});
},

+ 31 other calls in file

i.js

GitHub: nasolodar/test

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 * @return {Model[]} Parsed model list possibly containing additional pivot models.
 */
parsePivot(models) {
  return _.map(models, (model) => {
    // Separate pivot attributes.
    const grouped = _.reduce(
      model.attributes,
      (acc, value, key) => {
        if (hasPivotPrefix(key)) {
          acc.pivot[removePivotPrefix(key)] = value;

reduce.js

GitHub: norjs/cloud-backend

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		console.log("#4 req=", req, " res=", res);
		return "hello";
	}
];


var func = _.reduce(
	funcs,
	(a, b) => (req, res, next) => a(req, res, err => {
		if(err !== undefined) throw err;
		return b(req, res, next);

index.js

GitHub: nodejs-tutorials/hello-ghost

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    permission: Models.Permission,
    setting:    Models.Settings
};

// Iterate through the object types, i.e. ['post', 'tag', 'user']
return _.reduce(objTypes, function (objTypeHandlers, objType) {
    // Grab the TargetModel through the objectTypeModelMap
    var TargetModel = objectTypeModelMap[objType];

    // Create the 'handler' for the object type;

index.js

GitHub: web-tiny/utils

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  }
  return a;
}


function lameCSV (str) {
  return _.reduce(str.split('\n'), (table, row) => {
    table.push(_.map(row.split(','), c => c.trim()));
    return table;
  }, [])
}

dom_conf.js

GitHub: jeewonahn/jeewonahn.github.io

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.all([
  queryFunction('SELECT name_eng, name_kor FROM user'),
  queryFunction('SELECT paper_doms_conf.id, paper_status.name_eng as paper_name_eng, paper_status.name_kor as paper_name_kor, paper_conf_presentation.name_eng, paper_conf_presentation.name_kor, project.subject, research.title as research_title, conf_city, conf_startdate, conf_enddate, conf_name, author1, author2, author3, author4, author5, author6, author7, author8, paper_doms_conf.title, year, month, volumn, startpage, endpage, paper_file, coverpage_file, listpage_file, firstpage_file FROM paper_doms_conf LEFT JOIN paper_status ON paper_doms_conf.statusid = paper_status.id LEFT JOIN paper_conf_presentation ON paper_doms_conf.presentationid = paper_conf_presentation.id LEFT JOIN project ON paper_doms_conf.projectid = project.id LEFT JOIN research ON paper_doms_conf.researchid = research.id'),
])
.then(([member_rows, rows]) => {
  const name_map = _.reduce(member_rows, (result, row) => {
    return _.defaults(result, { [row.name_kor]: row.name_eng });
  }, {});

  var dateArr = [];

+ 17 other calls in file

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