perf: bring back v5 perf improvements and add some new ones

packages/formatters/src/number.js

@@ -1,24 +1,16 @@
-function toFixedDecimals(value, decimals) {
-  return value.toFixed(decimals);
-}
-
-function replaceSeparator(value, separator) {
-  return value.replace('.', separator);
-}
-
 export default function numberFormatter(opts = {}) {
   if (opts.separator) {
     if (opts.decimals) {
       return (value) =>
-        replaceSeparator(toFixedDecimals(value, opts.decimals), opts.separator);
+        value.toFixed(opts.decimals).replace('.', opts.separator);
     }
 
-    return (value) => replaceSeparator(value.toString(), opts.separator);
+    return (value) => `${value}`.replace('.', opts.separator);
   }
 
   if (opts.decimals) {
-    return (value) => toFixedDecimals(value, opts.decimals);
+    return (value) => value.toFixed(opts.decimals);
   }
 
-  return (value) => value.toString();
+  return (value) => `${value}`;
 }

packages/formatters/src/string.js

@@ -5,7 +5,7 @@ export default function stringFormatter(opts = {}) {
       ? opts.escapedQuote
       : `${quote}${quote}`;
 
-  if (!quote) {
+  if (!quote || quote === escapedQuote) {
     return (value) => value;
   }
 

packages/parsers/src/BaseParser.js

@@ -1,10 +1,10 @@
 import lodashGet from 'lodash.get';
-import { getProp } from './utils.js';
 import defaultFormatter from '@json2csv/formatters/default';
 import numberFormatterCtor from '@json2csv/formatters/number';
 import stringFormatterCtor from '@json2csv/formatters/string';
 import symbolFormatterCtor from '@json2csv/formatters/symbol';
 import objectFormatterCtor from '@json2csv/formatters/object';
+import { getProp, flattenReducer, fastJoin } from './utils.js';
 
 export default class JSON2CSVBase {
   constructor(opts) {
@@ -118,10 +118,13 @@ export default class JSON2CSVBase {
    *
    * @returns {String} titles as a string
    */
-  getHeader(fields) {
-    return fields
-      .map((fieldInfo) => this.opts.formatters.header(fieldInfo.label))
-      .join(this.opts.delimiter);
+  getHeader() {
+    return fastJoin(
+      this.opts.fields.map((fieldInfo) =>
+        this.opts.formatters.header(fieldInfo.label)
+      ),
+      this.opts.delimiter
+    );
   }
 
   /**
@@ -130,7 +133,8 @@ export default class JSON2CSVBase {
    */
   preprocessRow(row) {
     return this.opts.transforms.reduce(
-      (rows, transform) => rows.flatMap((row) => transform(row)),
+      (rows, transform) =>
+        rows.map((row) => transform(row)).reduce(flattenReducer, []),
       [row]
     );
   }
@@ -141,12 +145,12 @@ export default class JSON2CSVBase {
    * @param {Object} row JSON object to be converted in a CSV row
    * @returns {String} CSV string (row)
    */
-  processRow(row, fields) {
+  processRow(row) {
     if (!row) {
       return undefined;
     }
 
-    const processedRow = fields.map((fieldInfo) =>
+    const processedRow = this.opts.fields.map((fieldInfo) =>
       this.processCell(row, fieldInfo)
     );
 
@@ -157,7 +161,7 @@ export default class JSON2CSVBase {
       return undefined;
     }
 
-    return processedRow.join(this.opts.delimiter);
+    return fastJoin(processedRow, this.opts.delimiter);
   }
 
   /**

packages/parsers/src/Parser.js

@@ -1,4 +1,5 @@
 import JSON2CSVBase from './BaseParser.js';
+import { flattenReducer, fastJoin } from './utils.js';
 
 export default class JSON2CSVParser extends JSON2CSVBase {
   constructor(opts) {
@@ -11,12 +12,12 @@ export default class JSON2CSVParser extends JSON2CSVBase {
    * @returns {String} The CSV formated data as a string
    */
   parse(data) {
-    const processedData = this.preprocessData(data, this.opts.fields);
+    const preprocessedData = this.preprocessData(data);
 
-    const fields =
+    this.opts.fields =
       this.opts.fields ||
       this.preprocessFieldsInfo(
-        processedData.reduce((fields, item) => {
+        preprocessedData.reduce((fields, item) => {
           Object.keys(item).forEach((field) => {
             if (!fields.includes(field)) {
               fields.push(field);
@@ -27,8 +28,8 @@ export default class JSON2CSVParser extends JSON2CSVBase {
         }, [])
       );
 
-    const header = this.opts.header ? this.getHeader(fields) : '';
-    const rows = this.processData(processedData, fields);
+    const header = this.opts.header ? this.getHeader() : '';
+    const rows = this.processData(preprocessedData);
     const csv =
       (this.opts.withBOM ? '\ufeff' : '') +
       header +
@@ -44,11 +45,11 @@ export default class JSON2CSVParser extends JSON2CSVBase {
    *
    * @param {Array|Object} data Array or object to be converted to CSV
    */
-  preprocessData(data, fields) {
+  preprocessData(data) {
     const processedData = Array.isArray(data) ? data : [data];
 
     if (
-      !fields &&
+      !this.opts.fields &&
       (processedData.length === 0 || typeof processedData[0] !== 'object')
     ) {
       throw new Error(
@@ -58,7 +59,9 @@ export default class JSON2CSVParser extends JSON2CSVBase {
 
     if (this.opts.transforms.length === 0) return processedData;
 
-    return processedData.flatMap((row) => this.preprocessRow(row));
+    return processedData
+      .map((row) => this.preprocessRow(row))
+      .reduce(flattenReducer, []);
   }
 
   /**
@@ -67,10 +70,10 @@ export default class JSON2CSVParser extends JSON2CSVBase {
    * @param {Array} data Array of JSON objects to be converted to CSV
    * @returns {String} CSV string (body)
    */
-  processData(data, fields) {
-    return data
-      .map((row) => this.processRow(row, fields))
-      .filter((row) => row) // Filter empty rows
-      .join(this.opts.eol);
+  processData(data) {
+    return fastJoin(
+      data.map((row) => this.processRow(row)).filter((row) => row), // Filter empty rows
+      this.opts.eol
+    );
   }
 }

packages/parsers/src/StreamParser.js

@@ -124,7 +124,7 @@ export default class JSON2CSVStreamParser extends JSON2CSVBase {
     }
 
     if (this.opts.header) {
-      const header = this.getHeader(this.opts.fields);
+      const header = this.getHeader();
       this.onHeader(header);
       this.onData(header);
       this._hasWritten = true;
@@ -147,7 +147,7 @@ export default class JSON2CSVStreamParser extends JSON2CSVBase {
     }
 
     processedData.forEach((row) => {
-      const line = this.processRow(row, this.opts.fields);
+      const line = this.processRow(row);
       if (line === undefined) return;
       this.onLine(line);
       this.onData(this._hasWritten ? this.opts.eol + line : line);

packages/parsers/src/utils.js

@@ -1,3 +1,31 @@
 export function getProp(obj, path, defaultValue) {
-  return obj[path] === undefined ? defaultValue : obj[path];
+  const value = obj[path];
+  return value === undefined ? defaultValue : value;
+}
+
+export function flattenReducer(acc, arr) {
+  try {
+    // This is faster but susceptible to `RangeError: Maximum call stack size exceeded`
+    acc.push(...arr);
+    return acc;
+  } catch (err) {
+    // Fallback to a slower but safer option
+    return acc.concat(arr);
+  }
+}
+
+export function fastJoin(arr, separator) {
+  let isFirst = true;
+  return arr.reduce((acc, elem) => {
+    if (elem === null || elem === undefined) {
+      elem = '';
+    }
+
+    if (isFirst) {
+      isFirst = false;
+      return `${elem}`;
+    }
+
+    return `${acc}${separator}${elem}`;
+  }, '');
 }

packages/transforms/src/unwind.js

@@ -1,5 +1,5 @@
 import lodashGet from 'lodash.get';
-import { setProp, unsetProp } from './utils.js';
+import { setProp, unsetProp, flattenReducer } from './utils.js';
 
 function getUnwindablePaths(obj, currentPath) {
   return Object.keys(obj).reduce((unwindablePaths, key) => {
@@ -20,7 +20,8 @@ function getUnwindablePaths(obj, currentPath) {
       unwindablePaths.push(newPath);
       unwindablePaths = unwindablePaths.concat(
         value
-          .flatMap((arrObj) => getUnwindablePaths(arrObj, newPath))
+          .map((arrObj) => getUnwindablePaths(arrObj, newPath))
+          .reduce(flattenReducer, [])
           .filter((item, index, arr) => arr.indexOf(item) !== index)
       );
     }

packages/transforms/src/utils.js

@@ -32,3 +32,14 @@ export function unsetProp(obj, path) {
     {}
   );
 }
+
+export function flattenReducer(acc, arr) {
+  try {
+    // This is faster but susceptible to `RangeError: Maximum call stack size exceeded`
+    acc.push(...arr);
+    return acc;
+  } catch (err) {
+    // Fallback to a slower but safer option
+    return acc.concat(arr);
+  }
+}