add local eslint rule rule for banning concat and new performance test

eslint-local-rules.js

@@ -1,6 +1,30 @@
 'use strict';
 
 module.exports = {
+ 'ban-concat': {
+ meta: {
+ type: 'suggestion',
+ schema: [],
+ },
+ create(context) {
+ return {
+ CallExpression(node) {
+ if (
+ (
+ node.callee.property &&
+ node.callee.property.name === 'concat' &&
+ node.callee?.object?.name !== 'Buffer'
+ ) || (
+ node.callee?.object?.property?.name === 'concat' &&
+ node.callee?.object?.object?.type === 'ArrayExpression'
+ )
+ ) {
+ context.report({node, message: 'Use obj.push(...data) instead of obj = obj.concat(data)'})
+ }
+ },
+ }
+ },
+ },
  'ban-foreach': {
  meta: {
  type: 'suggestion',

package.json

@@ -87,6 +87,7 @@
  "error",
  "always"
  ],
+ "local-rules/ban-concat": 2,
  "local-rules/ban-foreach": 2,
  "local-rules/import-extensions": 2
  }

src/bidi.js

@@ -101,8 +101,7 @@ Bidi.prototype.registerFeatures = function (script, tags) {
  if (!Object.prototype.hasOwnProperty.call(this.featuresTags, script)) {
  this.featuresTags[script] = supportedTags;
  } else {
- this.featuresTags[script] =
- this.featuresTags[script].concat(supportedTags);
+ this.featuresTags[script].push(...supportedTags);
  }
 };
 

src/features/arab/arabicPresentationForms.js

@@ -12,7 +12,8 @@ import applySubstitution from '../applySubstitution.js';
  * @param {ContextParams} charContextParams context params of a char
  */
 function willConnectPrev(charContextParams) {
- let backtrack = [].concat(charContextParams.backtrack);
+ let backtrack = [...charContextParams.backtrack];
+
  for (let i = backtrack.length - 1; i >= 0; i--) {
  const prevChar = backtrack[i];
  const isolated = isIsolatedArabicChar(prevChar);

src/features/featureQuery.js

@@ -128,7 +128,7 @@ function chainingSubstitutionFormat3(contextParams, subtable) {
  subtable.lookaheadCoverage, lookaheadParams
  );
  // BACKTRACK LOOKUP //
- let backtrackContext = [].concat(contextParams.backtrack);
+ let backtrackContext = [...contextParams.backtrack];
  backtrackContext.reverse();
  while (backtrackContext.length && isTashkeelArabicChar(backtrackContext[0].char)) {
  backtrackContext.shift();
@@ -375,7 +375,7 @@ FeatureQuery.prototype.lookupFeature = function (query) {
  `for script '${query.script}'.`
  );
  const lookups = this.getFeatureLookups(feature);
- const substitutions = [].concat(contextParams.context);
+ const substitutions = [...contextParams.context];
  for (let l = 0; l < lookups.length; l++) {
  const lookupTable = lookups[l];
  const subtables = this.getLookupSubtables(lookupTable);

src/path.js

@@ -76,8 +76,7 @@ function optimizeCommands(commands) {
  }
  }
  }
- commands = [].concat.apply([], subpaths); // flatten again
- return commands;
+ return [...subpaths.flat()]; // flatten again
 }
 
 /**

src/substitution.js

@@ -161,7 +161,7 @@ Substitution.prototype.getLigatures = function(feature, script, language) {
  for (let k = 0; k < ligSet.length; k++) {
  const lig = ligSet[k];
  ligatures.push({
- sub: [startGlyph].concat(lig.components),
+ sub: [startGlyph, ...lig.components],
  by: lig.ligGlyph
  });
  }
@@ -309,15 +309,19 @@ Substitution.prototype.getFeature = function(feature, script, language) {
  switch (feature) {
  case 'aalt':
  case 'salt':
- return this.getSingle(feature, script, language)
- .concat(this.getAlternates(feature, script, language));
+ return [
+ ...this.getSingle(feature, script, language),
+ ...this.getAlternates(feature, script, language)
+ ];
  case 'dlig':
  case 'liga':
  case 'rlig':
  return this.getLigatures(feature, script, language);
  case 'ccmp':
- return this.getMultiple(feature, script, language)
- .concat(this.getLigatures(feature, script, language));
+ return [
+ ...this.getMultiple(feature, script, language),
+ ...this.getLigatures(feature, script, language)
+ ]; 
  case 'stch':
  return this.getMultiple(feature, script, language);
  }

src/table.js

@@ -85,7 +85,7 @@ function recordList(itemName, records, itemCallback) {
  let fields = [];
  fields[0] = {name: itemName + 'Count', type: 'USHORT', value: count};
  for (let i = 0; i < count; i++) {
- fields = fields.concat(itemCallback(records[i], i));
+ fields.push(...itemCallback(records[i], i));
  }
  return fields;
 }
@@ -101,21 +101,19 @@ function recordList(itemName, records, itemCallback) {
  */
 function Coverage(coverageTable) {
  if (coverageTable.format === 1) {
- Table.call(this, 'coverageTable',
- [{name: 'coverageFormat', type: 'USHORT', value: 1}]
-  .concat(ushortList('glyph', coverageTable.glyphs))
- );
+ Table.call(this, 'coverageTable', [
+ {name: 'coverageFormat', type: 'USHORT', value: 1},
+ ...ushortList('glyph', coverageTable.glyphs)
+ ]); 
  } else if (coverageTable.format === 2) {
- Table.call(this, 'coverageTable',
- [{name: 'coverageFormat', type: 'USHORT', value: 2}]
- .concat(recordList('rangeRecord', coverageTable.ranges, function(RangeRecord, i) {
- return [
- {name: 'startGlyphID' + i, type: 'USHORT', value: RangeRecord.start},
- {name: 'endGlyphID' + i, type: 'USHORT', value: RangeRecord.end},
- {name: 'startCoverageIndex' + i, type: 'USHORT', value: RangeRecord.index},
- ];
- }))
- );
+ Table.call(this, 'coverageTable', [
+ {name: 'coverageFormat', type: 'USHORT', value: 2},
+ ...recordList('rangeRecord', coverageTable.ranges, (RangeRecord, i) => [
+ {name: 'startGlyphID' + i, type: 'USHORT', value: RangeRecord.start},
+ {name: 'endGlyphID' + i, type: 'USHORT', value: RangeRecord.end},
+ {name: 'startCoverageIndex' + i, type: 'USHORT', value: RangeRecord.index},
+ ])
+ ]); 
  } else {
  check.assert(false, 'Coverage format must be 1 or 2.');
  }
@@ -134,19 +132,22 @@ function ScriptList(scriptListTable) {
  {name: 'script' + i, type: 'TABLE', value: new Table('scriptTable', [
  {name: 'defaultLangSys', type: 'TABLE', value: new Table('defaultLangSys', [
  {name: 'lookupOrder', type: 'USHORT', value: 0},
- {name: 'reqFeatureIndex', type: 'USHORT', value: defaultLangSys.reqFeatureIndex}]
- .concat(ushortList('featureIndex', defaultLangSys.featureIndexes)))}
- ].concat(recordList('langSys', script.langSysRecords, function(langSysRecord, i) {
- const langSys = langSysRecord.langSys;
- return [
- {name: 'langSysTag' + i, type: 'TAG', value: langSysRecord.tag},
- {name: 'langSys' + i, type: 'TABLE', value: new Table('langSys', [
- {name: 'lookupOrder', type: 'USHORT', value: 0},
- {name: 'reqFeatureIndex', type: 'USHORT', value: langSys.reqFeatureIndex}
- ].concat(ushortList('featureIndex', langSys.featureIndexes)))}
- ];
- })))}
- ];
+ {name: 'reqFeatureIndex', type: 'USHORT', value: defaultLangSys.reqFeatureIndex},
+ ...ushortList('featureIndex', defaultLangSys.featureIndexes)
+ ])},
+ ...recordList('langSys', script.langSysRecords, (langSysRecord, i) => {
+ const langSys = langSysRecord.langSys;
+ return [
+ {name: 'langSysTag' + i, type: 'TAG', value: langSysRecord.tag},
+ {name: 'langSys' + i, type: 'TABLE', value: new Table('langSys', [
+ {name: 'lookupOrder', type: 'USHORT', value: 0},
+ {name: 'reqFeatureIndex', type: 'USHORT', value: langSys.reqFeatureIndex},
+ ...ushortList('featureIndex', langSys.featureIndexes)
+ ])}
+ ];
+ })
+ ])}
+ ]; 
  })
  );
 }
@@ -168,8 +169,9 @@ function FeatureList(featureListTable) {
  {name: 'featureTag' + i, type: 'TAG', value: featureRecord.tag},
  {name: 'feature' + i, type: 'TABLE', value: new Table('featureTable', [
  {name: 'featureParams', type: 'USHORT', value: feature.featureParams},
- ].concat(ushortList('lookupListIndex', feature.lookupListIndexes)))}
- ];
+ ...ushortList('lookupListIndex', feature.lookupListIndexes)
+ ])}
+ ]; 
  })
  );
 }
@@ -190,8 +192,9 @@ function LookupList(lookupListTable, subtableMakers) {
  check.assert(!!subtableCallback, 'Unable to write GSUB lookup type ' + lookupTable.lookupType + ' tables.');
  return new Table('lookupTable', [
  {name: 'lookupType', type: 'USHORT', value: lookupTable.lookupType},
- {name: 'lookupFlag', type: 'USHORT', value: lookupTable.lookupFlag}
- ].concat(tableList('subtable', lookupTable.subtables, subtableCallback)));
+ {name: 'lookupFlag', type: 'USHORT', value: lookupTable.lookupFlag},
+ ...tableList('subtable', lookupTable.subtables, subtableCallback)
+ ]); 
  }));
 }
 LookupList.prototype = Object.create(Table.prototype);
@@ -209,24 +212,21 @@ LookupList.prototype.constructor = LookupList;
  */
 function ClassDef(classDefTable) {
  if (classDefTable.format === 1) {
- Table.call(this, 'classDefTable',
- [
- {name: 'classFormat', type: 'USHORT', value: 1},
- {name: 'startGlyphID', type: 'USHORT', value: classDefTable.startGlyph}
- ]
- .concat(ushortList('glyph', classDefTable.classes))
- );
+ Table.call(this, 'classDefTable', [
+ {name: 'classFormat', type: 'USHORT', value: 1},
+ {name: 'startGlyphID', type: 'USHORT', value: classDefTable.startGlyph},
+ ...ushortList('glyph', classDefTable.classes)
+ ]); 
  } else if (classDefTable.format === 2) {
- Table.call(this, 'classDefTable',
- [{name: 'classFormat', type: 'USHORT', value: 2}]
- .concat(recordList('rangeRecord', classDefTable.ranges, function(RangeRecord, i) {
- return [
- {name: 'startGlyphID' + i, type: 'USHORT', value: RangeRecord.start},
- {name: 'endGlyphID' + i, type: 'USHORT', value: RangeRecord.end},
- {name: 'class' + i, type: 'USHORT', value: RangeRecord.classId},
- ];
- }))
- );
+ Table.call(this, 'classDefTable', [
+ {name: 'classFormat', type: 'USHORT', value: 2},
+ ...recordList('rangeRecord', classDefTable.ranges, (RangeRecord, i) => [
+ {name: 'startGlyphID' + i, type: 'USHORT', value: RangeRecord.start},
+ {name: 'endGlyphID' + i, type: 'USHORT', value: RangeRecord.end},
+ {name: 'class' + i, type: 'USHORT', value: RangeRecord.classId},
+ ])
+ ]);
+
  } else {
  check.assert(false, 'Class format must be 1 or 2.');
  }

src/tables/avar.js

@@ -20,10 +20,10 @@ function makeAvarSegmentMap(n, axis) {
  let axisValueMaps = [];
  for (let i = 0; i < axis.axisValueMaps.length; i++) {
  const valueMap = makeAvarAxisValueMap(`${n}_${i}`, axis.axisValueMaps[i]);
- axisValueMaps = axisValueMaps.concat(valueMap.fields);
+ axisValueMaps.push(...valueMap.fields);
  }
 
- returnTable.fields = returnTable.fields.concat(axisValueMaps);
+ returnTable.fields.push(...axisValueMaps);
 
  return returnTable;
 }
@@ -40,7 +40,7 @@ function makeAvarTable(avar, fvar) {
 
  for (let i = 0; i < avar.axisSegmentMaps.length; i++) {
  const axisRecord = makeAvarSegmentMap(i, avar.axisSegmentMaps[i]);
- result.fields = result.fields.concat(axisRecord.fields);
+ result.fields.push(...axisRecord.fields);
  }
 
  return result;

src/tables/fvar.js

@@ -99,11 +99,11 @@ function makeFvarTable(fvar, names) {
  result.offsetToData = result.sizeOf();
 
  for (let i = 0; i < fvar.axes.length; i++) {
- result.fields = result.fields.concat(makeFvarAxis(i, fvar.axes[i], names));
+ result.fields.push(...makeFvarAxis(i, fvar.axes[i], names));
  }
 
  for (let j = 0; j < fvar.instances.length; j++) {
- result.fields = result.fields.concat(makeFvarInstance(j, fvar.instances[j], fvar.axes, names));
+ result.fields.push(...makeFvarInstance(j, fvar.instances[j], fvar.axes, names));
  }
 
  return result;

src/tables/glyf.js

@@ -290,7 +290,7 @@ function buildPath(glyphs, glyph) {
  transform.dy = firstPt.y - secondPt.y;
  transformedPoints = transformPoints(componentGlyph.points, transform);
  }
- glyph.points = glyph.points.concat(transformedPoints);
+ glyph.points.push(...transformedPoints);
  }
  }
  }