Merge pull request #995 from zloirock/number-to-exponential

zloirock · Dec 9, 2021 · 816e855 · 816e855
2 parents 65c36d8 + 7708d24
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ## Changelog
 ##### Unreleased
+- Added `Number.prototype.toExponential` method polyfill with many different fixes for the most engines
 - [`Array` grouping proposal](https://github.com/tc39/proposal-array-grouping):
   - Moved to the stage 2
   - Added `Array.prototype.groupByMap` method

diff --git a/README.md b/README.md
@@ -895,10 +895,11 @@ Module [`es.number.constructor`](https://github.com/zloirock/core-js/blob/master
 Number('0b1010101'); // => 85
 Number('0o7654321'); // => 2054353
 ```
-Modules [`es.number.epsilon`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.epsilon.js), [`es.number.is-finite`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-finite.js), [`es.number.is-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-integer.js), [`es.number.is-nan`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-nan.js), [`es.number.is-safe-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-safe-integer.js), [`es.number.max-safe-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.max-safe-integer.js), [`es.number.min-safe-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.min-safe-integer.js), [`es.number.parse-float`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.parse-float.js), [`es.number.parse-int`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.parse-int.js), [`es.number.to-fixed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.to-fixed.js), [`es.number.to-precision`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.to-precision.js), [`es.parse-int`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.parse-int.js), [`es.parse-float`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.parse-float.js).
+Modules [`es.number.epsilon`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.epsilon.js), [`es.number.is-finite`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-finite.js), [`es.number.is-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-integer.js), [`es.number.is-nan`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-nan.js), [`es.number.is-safe-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.is-safe-integer.js), [`es.number.max-safe-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.max-safe-integer.js), [`es.number.min-safe-integer`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.min-safe-integer.js), [`es.number.parse-float`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.parse-float.js), [`es.number.parse-int`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.parse-int.js), [`es.number.to-exponential`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.to-exponential.js), [`es.number.to-fixed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.to-fixed.js), [`es.number.to-precision`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.number.to-precision.js), [`es.parse-int`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.parse-int.js), [`es.parse-float`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.parse-float.js).
 ```js
 class Number {
   constructor(value: any): number;
+  toExponential(digits: number): string;
   toFixed(digits: number): string;
   toPrecision(precision: number): string;
   static isFinite(number: any): boolean;
@@ -928,6 +929,7 @@ core-js(-pure)/es|stable|features/number/parse-int
 core-js(-pure)/es|stable|features/number/epsilon
 core-js(-pure)/es|stable|features/number/max-safe-integer
 core-js(-pure)/es|stable|features/number/min-safe-integer
+core-js(-pure)/es|stable|features/number/to-exponential
 core-js(-pure)/es|stable|features/number/to-fixed
 core-js(-pure)/es|stable|features/number/to-precision
 core-js(-pure)/es|stable|features/parse-float

diff --git a/packages/core-js-compat/src/data.mjs b/packages/core-js-compat/src/data.mjs
@@ -620,6 +620,12 @@ export const data = {
     firefox: '39',
     safari: '9.0',
   },
+  'es.number.to-exponential': {
+    chrome: '26',
+    edge: '18',
+    firefox: '50',
+    safari: '11',
+  },
   'es.number.to-fixed': {
     chrome: '26',
     firefox: '4',

diff --git a/packages/core-js-compat/src/modules-by-versions.mjs b/packages/core-js-compat/src/modules-by-versions.mjs
@@ -112,6 +112,7 @@ export default {
     'esnext.typed-array.from-async',
   ],
   '3.20': [
+    'es.number.to-exponential',
     'esnext.array.group-by-map',
     'esnext.array.to-reversed',
     'esnext.array.to-sorted',

diff --git a/packages/core-js/es/number/index.js b/packages/core-js/es/number/index.js
@@ -8,6 +8,7 @@ require('../../modules/es.number.max-safe-integer');
 require('../../modules/es.number.min-safe-integer');
 require('../../modules/es.number.parse-float');
 require('../../modules/es.number.parse-int');
+require('../../modules/es.number.to-exponential');
 require('../../modules/es.number.to-fixed');
 require('../../modules/es.number.to-precision');
 var path = require('../../internals/path');

diff --git a/packages/core-js/es/number/to-exponential.js b/packages/core-js/es/number/to-exponential.js
@@ -0,0 +1,4 @@
+require('../../modules/es.number.to-exponential');
+var entryUnbind = require('../../internals/entry-unbind');
+
+module.exports = entryUnbind('Number', 'toExponential');
diff --git a/packages/core-js/es/number/virtual/index.js b/packages/core-js/es/number/virtual/index.js
@@ -1,3 +1,4 @@
+require('../../../modules/es.number.to-exponential');
 require('../../../modules/es.number.to-fixed');
 require('../../../modules/es.number.to-precision');
 var entryVirtual = require('../../../internals/entry-virtual');

diff --git a/packages/core-js/es/number/virtual/to-exponential.js b/packages/core-js/es/number/virtual/to-exponential.js
@@ -0,0 +1,4 @@
+require('../../../modules/es.number.to-exponential');
+var entryVirtual = require('../../../internals/entry-virtual');
+
+module.exports = entryVirtual('Number').toExponential;
diff --git a/packages/core-js/features/number/to-exponential.js b/packages/core-js/features/number/to-exponential.js
@@ -0,0 +1,3 @@
+var parent = require('../../stable/number/to-exponential');
+
+module.exports = parent;
diff --git a/packages/core-js/features/number/virtual/to-exponential.js b/packages/core-js/features/number/virtual/to-exponential.js
@@ -0,0 +1,3 @@
+var parent = require('../../../stable/number/virtual/to-exponential');
+
+module.exports = parent;
diff --git a/packages/core-js/internals/math-log10.js b/packages/core-js/internals/math-log10.js
@@ -0,0 +1,7 @@
+var log = Math.log;
+var LOG10E = Math.LOG10E;
+
+// eslint-disable-next-line es/no-math-log10 -- safe
+module.exports = Math.log10 || function log10(x) {
+  return log(x) * LOG10E;
+};
diff --git a/packages/core-js/modules/es.math.log10.js b/packages/core-js/modules/es.math.log10.js
@@ -1,12 +1,8 @@
 var $ = require('../internals/export');
-
-var log = Math.log;
-var LOG10E = Math.LOG10E;
+var log10 = require('../internals/math-log10');
 
 // `Math.log10` method
 // https://tc39.es/ecma262/#sec-math.log10
 $({ target: 'Math', stat: true }, {
-  log10: function log10(x) {
-    return log(x) * LOG10E;
-  }
+  log10: log10
 });
diff --git a/packages/core-js/modules/es.number.to-exponential.js b/packages/core-js/modules/es.number.to-exponential.js
@@ -0,0 +1,98 @@
+'use strict';
+var $ = require('../internals/export');
+var global = require('../internals/global');
+var uncurryThis = require('../internals/function-uncurry-this');
+var toIntegerOrInfinity = require('../internals/to-integer-or-infinity');
+var thisNumberValue = require('../internals/this-number-value');
+var $repeat = require('../internals/string-repeat');
+var log10 = require('../internals/math-log10');
+var fails = require('../internals/fails');
+
+var RangeError = global.RangeError;
+var String = global.String;
+var isFinite = global.isFinite;
+var abs = Math.abs;
+var floor = Math.floor;
+var pow = Math.pow;
+var round = Math.round;
+var un$ToExponential = uncurryThis(1.0.toExponential);
+var repeat = uncurryThis($repeat);
+var stringSlice = uncurryThis(''.slice);
+
+// Edge 17-
+var ROUNDS_PROPERLY = un$ToExponential(-6.9e-11, 4) === '-6.9000e-11'
+  // IE11- && Edge 14-
+  && un$ToExponential(1.255, 2) === '1.25e+0';
+  // FF86-, enable after increasing maximum number of fraction digits in the implementation to 100
+  // && nativeToExponential.call(25, 0) === '3e+1';
+
+// IE8-
+var THROWS_ON_INFINITY_FRACTION = fails(function () {
+  un$ToExponential(1, Infinity);
+}) && fails(function () {
+  un$ToExponential(1, -Infinity);
+});
+
+// Safari <11 && FF <50
+var PROPER_NON_FINITE_THIS_CHECK = !fails(function () {
+  un$ToExponential(Infinity, Infinity);
+}) && !fails(function () {
+  un$ToExponential(NaN, Infinity);
+});
+
+var FORCED = !ROUNDS_PROPERLY || !THROWS_ON_INFINITY_FRACTION || !PROPER_NON_FINITE_THIS_CHECK;
+
+// `Number.prototype.toExponential` method
+// https://tc39.es/ecma262/#sec-number.prototype.toexponential
+$({ target: 'Number', proto: true, forced: FORCED }, {
+  toExponential: function toExponential(fractionDigits) {
+    var x = thisNumberValue(this);
+    if (fractionDigits === undefined) return un$ToExponential(x);
+    var f = toIntegerOrInfinity(fractionDigits);
+    if (!isFinite(x)) return String(x);
+    // TODO: ES2018 increased the maximum number of fraction digits to 100, need to improve the implementation
+    if (f < 0 || f > 20) throw RangeError('Incorrect fraction digits');
+    if (ROUNDS_PROPERLY) return un$ToExponential(x, f);
+    var s = '';
+    var m = '';
+    var e = 0;
+    var c = '';
+    var d = '';
+    if (x < 0) {
+      s = '-';
+      x = -x;
+    }
+    if (x === 0) {
+      e = 0;
+      m = repeat('0', f + 1);
+    } else {
+      // this block is based on https://gist.github.com/SheetJSDev/1100ad56b9f856c95299ed0e068eea08
+      // TODO: improve accuracy with big fraction digits
+      var l = log10(x);
+      e = floor(l);
+      var n = 0;
+      var w = pow(10, e - f);
+      n = round(x / w);
+      if (2 * x >= (2 * n + 1) * w) {
+        n += 1;
+      }
+      if (n >= pow(10, f + 1)) {
+        n /= 10;
+        e += 1;
+      }
+      m = String(n);
+    }
+    if (f !== 0) {
+      m = stringSlice(m, 0, 1) + '.' + stringSlice(m, 1);
+    }
+    if (e === 0) {
+      c = '+';
+      d = '0';
+    } else {
+      c = e > 0 ? '+' : '-';
+      d = String(abs(e));
+    }
+    m += 'e' + c + d;
+    return s + m;
+  }
+});
diff --git a/packages/core-js/modules/es.number.to-fixed.js b/packages/core-js/modules/es.number.to-fixed.js
@@ -83,6 +83,7 @@ $({ target: 'Number', proto: true, forced: FORCED }, {
     var result = '0';
     var e, z, j, k;
 
+    // TODO: ES2018 increased the maximum number of fraction digits to 100, need to improve the implementation
     if (fractDigits < 0 || fractDigits > 20) throw RangeError('Incorrect fraction digits');
     // eslint-disable-next-line no-self-compare -- NaN check
     if (number != number) return 'NaN';

diff --git a/packages/core-js/stable/number/to-exponential.js b/packages/core-js/stable/number/to-exponential.js
@@ -0,0 +1,3 @@
+var parent = require('../../es/number/to-exponential');
+
+module.exports = parent;
diff --git a/packages/core-js/stable/number/virtual/to-exponential.js b/packages/core-js/stable/number/virtual/to-exponential.js
@@ -0,0 +1,3 @@
+var parent = require('../../../es/number/virtual/to-exponential');
+
+module.exports = parent;
diff --git a/tests/commonjs.mjs b/tests/commonjs.mjs
@@ -148,10 +148,12 @@ for (PATH of ['core-js-pure', 'core-js']) {
     ok(load(NS, 'number/min-safe-integer') === -0x1FFFFFFFFFFFFF);
     ok(load(NS, 'number/parse-float')('1.5') === 1.5);
     ok(load(NS, 'number/parse-int')('2.1') === 2);
+    ok(load(NS, 'number/to-exponential')(1, 1) === '1.0e+0');
     ok(load(NS, 'number/to-fixed')(1, 1) === '1.0');
     ok(load(NS, 'number/to-precision')(1) === '1');
     ok(load(NS, 'parse-float')('1.5') === 1.5);
     ok(load(NS, 'parse-int')('2.1') === 2);
+    ok(load(NS, 'number/virtual/to-exponential').call(1, 1) === '1.0e+0');
     ok(load(NS, 'number/virtual/to-fixed').call(1, 1) === '1.0');
     ok(load(NS, 'number/virtual/to-precision').call(1) === '1');
     ok('toPrecision' in load(NS, 'number/virtual'));

diff --git a/tests/compat/tests.js b/tests/compat/tests.js
@@ -635,6 +635,21 @@ GLOBAL.tests = {
         && parseInt(WHITESPACES + '0x16') === 22;
     }
   },
+  'es.number.to-exponential': function () {
+    try {
+      1.0.toExponential(Infinity);
+    } catch (error) {
+      try {
+        1.0.toExponential(-Infinity);
+      } catch (error2) {
+        Infinity.toExponential(Infinity);
+        NaN.toExponential(Infinity);
+        return (-6.9e-11).toExponential(4) === '-6.9000e-11'
+          && 1.255.toExponential(2) === '1.25e+0';
+        // && 25.0.toExponential(0) === '3e+1';
+      }
+    }
+  },
   'es.number.to-fixed': function () {
     try {
       Number.prototype.toFixed.call({});

diff --git a/tests/pure/es.number.to-exponential.js b/tests/pure/es.number.to-exponential.js
@@ -0,0 +1,135 @@
+import toExponential from 'core-js-pure/features/number/virtual/to-exponential';
+
+QUnit.test('Number#toExponential', assert => {
+  assert.isFunction(toExponential);
+
+  assert.same(toExponential.call(0.00008, 3), '8.000e-5');
+  assert.same(toExponential.call(0.9, 0), '9e-1');
+  assert.same(toExponential.call(1.255, 2), '1.25e+0');
+  assert.same(toExponential.call(1843654265.0774949, 5), '1.84365e+9');
+  assert.same(toExponential.call(1000000000000000128.0, 0), '1e+18');
+
+  assert.same(toExponential.call(1), '1e+0');
+  assert.same(toExponential.call(1, 0), '1e+0');
+  assert.same(toExponential.call(1, 1), '1.0e+0');
+  assert.same(toExponential.call(1, 1.1), '1.0e+0');
+  assert.same(toExponential.call(1, 0.9), '1e+0');
+  assert.same(toExponential.call(1, '0'), '1e+0');
+  assert.same(toExponential.call(1, '1'), '1.0e+0');
+  assert.same(toExponential.call(1, '1.1'), '1.0e+0');
+  assert.same(toExponential.call(1, '0.9'), '1e+0');
+  assert.same(toExponential.call(1, NaN), '1e+0');
+  assert.same(toExponential.call(1, 'some string'), '1e+0');
+  assert.notThrows(() => toExponential.call(1, -0.1) === '1e+0');
+  assert.same(toExponential.call(new Number(1)), '1e+0');
+  assert.same(toExponential.call(new Number(1), 0), '1e+0');
+  assert.same(toExponential.call(new Number(1), 1), '1.0e+0');
+  assert.same(toExponential.call(new Number(1), 1.1), '1.0e+0');
+  assert.same(toExponential.call(new Number(1), 0.9), '1e+0');
+  assert.same(toExponential.call(new Number(1), '0'), '1e+0');
+  assert.same(toExponential.call(new Number(1), '1'), '1.0e+0');
+  assert.same(toExponential.call(new Number(1), '1.1'), '1.0e+0');
+  assert.same(toExponential.call(new Number(1), '0.9'), '1e+0');
+  assert.same(toExponential.call(new Number(1), NaN), '1e+0');
+  assert.same(toExponential.call(new Number(1), 'some string'), '1e+0');
+  assert.notThrows(() => toExponential.call(new Number(1), -0.1) === '1e+0');
+  assert.same(toExponential.call(NaN), 'NaN');
+  assert.same(toExponential.call(NaN, 0), 'NaN');
+  assert.same(toExponential.call(NaN, 1), 'NaN');
+  assert.same(toExponential.call(NaN, 1.1), 'NaN');
+  assert.same(toExponential.call(NaN, 0.9), 'NaN');
+  assert.same(toExponential.call(NaN, '0'), 'NaN');
+  assert.same(toExponential.call(NaN, '1'), 'NaN');
+  assert.same(toExponential.call(NaN, '1.1'), 'NaN');
+  assert.same(toExponential.call(NaN, '0.9'), 'NaN');
+  assert.same(toExponential.call(NaN, NaN), 'NaN');
+  assert.same(toExponential.call(NaN, 'some string'), 'NaN');
+  assert.notThrows(() => toExponential.call(NaN, -0.1) === 'NaN');
+
+  assert.same(toExponential.call(new Number(1e21)), '1e+21');
+  assert.same(toExponential.call(new Number(1e21), 0), '1e+21');
+  assert.same(toExponential.call(new Number(1e21), 1), '1.0e+21');
+  assert.same(toExponential.call(new Number(1e21), 1.1), '1.0e+21');
+  assert.same(toExponential.call(new Number(1e21), 0.9), '1e+21');
+  assert.same(toExponential.call(new Number(1e21), '0'), '1e+21');
+  assert.same(toExponential.call(new Number(1e21), '1'), '1.0e+21');
+  assert.same(toExponential.call(new Number(1e21), '1.1'), '1.0e+21');
+  assert.same(toExponential.call(new Number(1e21), '0.9'), '1e+21');
+  assert.same(toExponential.call(new Number(1e21), NaN), '1e+21');
+  assert.same(toExponential.call(new Number(1e21), 'some string'), '1e+21');
+
+  assert.same(toExponential.call(5, 19), '5.0000000000000000000e+0');
+
+  // ported from tests262, the license: https://github.com/tc39/test262/blob/main/LICENSE
+  assert.same(toExponential.call(123.456, 0), '1e+2');
+  assert.same(toExponential.call(123.456, 1), '1.2e+2');
+  assert.same(toExponential.call(123.456, 2), '1.23e+2');
+  assert.same(toExponential.call(123.456, 3), '1.235e+2');
+  assert.same(toExponential.call(123.456, 4), '1.2346e+2');
+  assert.same(toExponential.call(123.456, 5), '1.23456e+2');
+  assert.same(toExponential.call(123.456, 6), '1.234560e+2');
+  assert.same(toExponential.call(123.456, 7), '1.2345600e+2');
+  // assert.same(toExponential.call(123.456, 17), '1.23456000000000003e+2');
+  // assert.same(toExponential.call(123.456, 20), '1.23456000000000003070e+2');
+
+  assert.same(toExponential.call(-123.456, 0), '-1e+2');
+  assert.same(toExponential.call(-123.456, 1), '-1.2e+2');
+  assert.same(toExponential.call(-123.456, 2), '-1.23e+2');
+  assert.same(toExponential.call(-123.456, 3), '-1.235e+2');
+  assert.same(toExponential.call(-123.456, 4), '-1.2346e+2');
+  assert.same(toExponential.call(-123.456, 5), '-1.23456e+2');
+  assert.same(toExponential.call(-123.456, 6), '-1.234560e+2');
+  assert.same(toExponential.call(-123.456, 7), '-1.2345600e+2');
+  // assert.same(toExponential.call(-123.456, 17), '-1.23456000000000003e+2');
+  // assert.same(toExponential.call(-123.456, 20), '-1.23456000000000003070e+2');
+
+  assert.same(toExponential.call(0.0001, 0), '1e-4');
+  assert.same(toExponential.call(0.0001, 1), '1.0e-4');
+  assert.same(toExponential.call(0.0001, 2), '1.00e-4');
+  assert.same(toExponential.call(0.0001, 3), '1.000e-4');
+  assert.same(toExponential.call(0.0001, 4), '1.0000e-4');
+  // assert.same(toExponential.call(0.0001, 16), '1.0000000000000000e-4');
+  // assert.same(toExponential.call(0.0001, 17), '1.00000000000000005e-4');
+  // assert.same(toExponential.call(0.0001, 18), '1.000000000000000048e-4');
+  // assert.same(toExponential.call(0.0001, 19), '1.0000000000000000479e-4');
+  // assert.same(toExponential.call(0.0001, 20), '1.00000000000000004792e-4');
+
+  assert.same(toExponential.call(0.9999, 0), '1e+0');
+  assert.same(toExponential.call(0.9999, 1), '1.0e+0');
+  assert.same(toExponential.call(0.9999, 2), '1.00e+0');
+  assert.same(toExponential.call(0.9999, 3), '9.999e-1');
+  assert.same(toExponential.call(0.9999, 4), '9.9990e-1');
+  // assert.same(toExponential.call(0.9999, 16), '9.9990000000000001e-1');
+  // assert.same(toExponential.call(0.9999, 17), '9.99900000000000011e-1');
+  // assert.same(toExponential.call(0.9999, 18), '9.999000000000000110e-1');
+  // assert.same(toExponential.call(0.9999, 19), '9.9990000000000001101e-1');
+  // assert.same(toExponential.call(0.9999, 20), '9.99900000000000011013e-1');
+
+  assert.same(toExponential.call(25, 0), '3e+1');
+  assert.same(toExponential.call(12345, 3), '1.235e+4');
+
+  assert.same(toExponential.call(Number.prototype, 0), '0e+0', 'Number.prototype, 0');
+  assert.same(toExponential.call(0, 0), '0e+0', '0, 0');
+  assert.same(toExponential.call(-0, 0), '0e+0', '-0, 0');
+  assert.same(toExponential.call(0, -0), '0e+0', '0, -0');
+  assert.same(toExponential.call(-0, -0), '0e+0', '-0, -0');
+  assert.same(toExponential.call(0, 1), '0.0e+0', '0 and 1');
+  assert.same(toExponential.call(0, 2), '0.00e+0', '0 and 2');
+  assert.same(toExponential.call(0, 7), '0.0000000e+0', '0 and 7');
+  assert.same(toExponential.call(0, 20), '0.00000000000000000000e+0', '0 and 20');
+  assert.same(toExponential.call(-0, 1), '0.0e+0', '-0 and 1');
+  assert.same(toExponential.call(-0, 2), '0.00e+0', '-0 and 2');
+  assert.same(toExponential.call(-0, 7), '0.0000000e+0', '-0 and 7');
+  assert.same(toExponential.call(-0, 20), '0.00000000000000000000e+0', '-0 and 20');
+
+  assert.same(toExponential.call(NaN, 1000), 'NaN', 'NaN check before fractionDigits check');
+  assert.same(toExponential.call(Infinity, 1000), 'Infinity', 'Infinity check before fractionDigits check');
+  assert.notThrows(() => toExponential.call(new Number(1e21), -0.1) === '1e+21');
+  assert.throws(() => toExponential.call(1.0, -101), RangeError, 'If f < 0 or f > 20 (100), throw a RangeError exception.');
+  assert.throws(() => toExponential.call(1.0, 101), RangeError, 'If f < 0 or f > 20 (100), throw a RangeError exception.');
+  assert.throws(() => toExponential.call({}, 1), TypeError, '? thisNumberValue(this value)');
+  assert.throws(() => toExponential.call('123', 1), TypeError, '? thisNumberValue(this value)');
+  assert.throws(() => toExponential.call(false, 1), TypeError, '? thisNumberValue(this value)');
+  assert.throws(() => toExponential.call(null, 1), TypeError, '? thisNumberValue(this value)');
+  assert.throws(() => toExponential.call(undefined, 1), TypeError, '? thisNumberValue(this value)');
+});