diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index 867858b4fb96..fd71b67c8653 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -476,7 +476,7 @@ module.exports = {
     'constructor-super': 'error',
     'default-case': 'off',
     'dot-notation': 'off',
-    eqeqeq: ['off', 'allow-null'],
+    eqeqeq: ['error', 'smart'],
     'eslint-comments/disable-enable-pair': ['error', {allowWholeFile: true}],
     'eslint-comments/no-unused-disable': 'error',
     'func-names': 'off',
diff --git a/docs/ExpectAPI.md b/docs/ExpectAPI.md
index dd03a3e76bfc..336564856346 100644
--- a/docs/ExpectAPI.md
+++ b/docs/ExpectAPI.md
@@ -789,7 +789,7 @@ For example, let's say that `drinkFlavor` is coded like this:
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -827,7 +827,7 @@ For example, let's say you have a `drinkFlavor` function that throws whenever th
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -1505,7 +1505,7 @@ expect.extend({
 expect.extend({
   async toBeDivisibleByExternalValue(received) {
     const externalValue = await getExternalValueFromRemoteSource();
-    const pass = received % externalValue == 0;
+    const pass = received % externalValue === 0;
     if (pass) {
       return {
         message: () =>
diff --git a/e2e/__tests__/jsonReporter.test.ts b/e2e/__tests__/jsonReporter.test.ts
index 03b01a6fccf2..87bed8e2c518 100644
--- a/e2e/__tests__/jsonReporter.test.ts
+++ b/e2e/__tests__/jsonReporter.test.ts
@@ -46,28 +46,28 @@ describe('JSON Reporter', () => {
     expect(jsonResult.numPendingTests).toBe(1);
 
     const noAncestors = jsonResult.testResults[0].assertionResults.find(
-      item => item.title == 'no ancestors',
+      item => item.title === 'no ancestors',
     );
     let expected = {ancestorTitles: [] as Array<string>};
     expect(noAncestors).toEqual(expect.objectContaining(expected));
     expect(noAncestors).toHaveProperty('duration', expect.any(Number));
 
     const addsNumbers = jsonResult.testResults[0].assertionResults.find(
-      item => item.title == 'adds numbers',
+      item => item.title === 'adds numbers',
     );
     expected = {ancestorTitles: ['sum']};
     expect(addsNumbers).toEqual(expect.objectContaining(expected));
     expect(addsNumbers).toHaveProperty('duration', expect.any(Number));
 
     const failsTheTest = jsonResult.testResults[0].assertionResults.find(
-      item => item.title == 'fails the test',
+      item => item.title === 'fails the test',
     );
     expected = {ancestorTitles: ['sum', 'failing tests']};
     expect(failsTheTest).toEqual(expect.objectContaining(expected));
     expect(failsTheTest).toHaveProperty('duration', expect.any(Number));
 
     const skipedTest = jsonResult.testResults[0].assertionResults.find(
-      item => item.title == 'skipped test',
+      item => item.title === 'skipped test',
     );
     expect(skipedTest).toHaveProperty('duration', null);
   });
@@ -99,19 +99,19 @@ describe('JSON Reporter', () => {
     expect(jsonResult.numPendingTests).toBe(1);
 
     const noAncestors = jsonResult.testResults[0].assertionResults.find(
-      item => item.title == 'no ancestors',
+      item => item.title === 'no ancestors',
     );
     let expected = {ancestorTitles: [] as Array<string>};
     expect(noAncestors).toEqual(expect.objectContaining(expected));
 
     const addsNumbers = jsonResult.testResults[0].assertionResults.find(
-      item => item.title == 'adds numbers',
+      item => item.title === 'adds numbers',
     );
     expected = {ancestorTitles: ['sum']};
     expect(addsNumbers).toEqual(expect.objectContaining(expected));
 
     const failsTheTest = jsonResult.testResults[0].assertionResults.find(
-      item => item.title == 'fails the test',
+      item => item.title === 'fails the test',
     );
     expected = {ancestorTitles: ['sum', 'failing tests']};
     expect(failsTheTest).toEqual(expect.objectContaining(expected));
diff --git a/packages/expect-utils/src/jasmineUtils.ts b/packages/expect-utils/src/jasmineUtils.ts
index 870b6b0b9f18..e4f6bc176810 100644
--- a/packages/expect-utils/src/jasmineUtils.ts
+++ b/packages/expect-utils/src/jasmineUtils.ts
@@ -84,7 +84,7 @@ function eq(
   }
 
   if (a instanceof Error && b instanceof Error) {
-    return a.message == b.message;
+    return a.message === b.message;
   }
 
   if (Object.is(a, b)) {
@@ -95,7 +95,7 @@ function eq(
     return false;
   }
   const className = Object.prototype.toString.call(a);
-  if (className != Object.prototype.toString.call(b)) {
+  if (className !== Object.prototype.toString.call(b)) {
     return false;
   }
   switch (className) {
@@ -116,7 +116,7 @@ function eq(
       // Coerce dates to numeric primitive values. Dates are compared by their
       // millisecond representations. Note that invalid dates with millisecond representations
       // of `NaN` are not equivalent.
-      return +a == +b;
+      return +a === +b;
     // RegExps are compared by their source patterns and flags.
     case '[object RegExp]':
       return a.source === b.source && a.flags === b.flags;
@@ -151,7 +151,7 @@ function eq(
   bStack.push(b);
   // Recursively compare objects and arrays.
   // Compare array lengths to determine if a deep comparison is necessary.
-  if (strictCheck && className == '[object Array]' && a.length !== b.length) {
+  if (strictCheck && className === '[object Array]' && a.length !== b.length) {
     return false;
   }
 
diff --git a/packages/expect/src/asymmetricMatchers.ts b/packages/expect/src/asymmetricMatchers.ts
index 92f7a67f539d..8eaa17d85bef 100644
--- a/packages/expect/src/asymmetricMatchers.ts
+++ b/packages/expect/src/asymmetricMatchers.ts
@@ -41,18 +41,6 @@ const utils = Object.freeze({
   subsetEquality,
 });
 
-function getPrototype(obj: object) {
-  if (Object.getPrototypeOf) {
-    return Object.getPrototypeOf(obj);
-  }
-
-  if (obj.constructor.prototype == obj) {
-    return null;
-  }
-
-  return obj.constructor.prototype;
-}
-
 export function hasProperty(
   obj: object | null,
   property: string | symbol,
@@ -65,7 +53,7 @@ export function hasProperty(
     return true;
   }
 
-  return hasProperty(getPrototype(obj), property);
+  return hasProperty(Object.getPrototypeOf(obj), property);
 }
 
 export abstract class AsymmetricMatcher<T>
@@ -108,35 +96,35 @@ class Any extends AsymmetricMatcher<any> {
   }
 
   asymmetricMatch(other: unknown) {
-    if (this.sample == String) {
-      return typeof other == 'string' || other instanceof String;
+    if (this.sample === String) {
+      return typeof other === 'string' || other instanceof String;
     }
 
-    if (this.sample == Number) {
-      return typeof other == 'number' || other instanceof Number;
+    if (this.sample === Number) {
+      return typeof other === 'number' || other instanceof Number;
     }
 
-    if (this.sample == Function) {
-      return typeof other == 'function' || other instanceof Function;
+    if (this.sample === Function) {
+      return typeof other === 'function' || other instanceof Function;
     }
 
-    if (this.sample == Boolean) {
-      return typeof other == 'boolean' || other instanceof Boolean;
+    if (this.sample === Boolean) {
+      return typeof other === 'boolean' || other instanceof Boolean;
     }
 
-    if (this.sample == BigInt) {
-      return typeof other == 'bigint' || other instanceof BigInt;
+    if (this.sample === BigInt) {
+      return typeof other === 'bigint' || other instanceof BigInt;
     }
 
-    if (this.sample == Symbol) {
-      return typeof other == 'symbol' || other instanceof Symbol;
+    if (this.sample === Symbol) {
+      return typeof other === 'symbol' || other instanceof Symbol;
     }
 
-    if (this.sample == Object) {
-      return typeof other == 'object';
+    if (this.sample === Object) {
+      return typeof other === 'object';
     }
 
-    if (this.sample == Array) {
+    if (this.sample === Array) {
       return Array.isArray(other);
     }
 
@@ -148,27 +136,27 @@ class Any extends AsymmetricMatcher<any> {
   }
 
   override getExpectedType() {
-    if (this.sample == String) {
+    if (this.sample === String) {
       return 'string';
     }
 
-    if (this.sample == Number) {
+    if (this.sample === Number) {
       return 'number';
     }
 
-    if (this.sample == Function) {
+    if (this.sample === Function) {
       return 'function';
     }
 
-    if (this.sample == Object) {
+    if (this.sample === Object) {
       return 'object';
     }
 
-    if (this.sample == Boolean) {
+    if (this.sample === Boolean) {
       return 'boolean';
     }
 
-    if (Array.isArray(this.sample)) {
+    if (this.sample === Array) {
       return 'array';
     }
 
diff --git a/packages/jest-haste-map/src/crawlers/__tests__/node.test.js b/packages/jest-haste-map/src/crawlers/__tests__/node.test.js
index be9bdf2ba68a..d2e357c275ed 100644
--- a/packages/jest-haste-map/src/crawlers/__tests__/node.test.js
+++ b/packages/jest-haste-map/src/crawlers/__tests__/node.test.js
@@ -105,7 +105,7 @@ jest.mock('graceful-fs', () => {
             ]),
           0,
         );
-      } else if (slash(dir) == '/error') {
+      } else if (slash(dir) === '/error') {
         setTimeout(() => callback({code: 'ENOTDIR'}, undefined), 0);
       }
     }),
diff --git a/packages/jest-repl/src/cli/runtime-cli.ts b/packages/jest-repl/src/cli/runtime-cli.ts
index 335af1858dc1..5997b040a769 100644
--- a/packages/jest-repl/src/cli/runtime-cli.ts
+++ b/packages/jest-repl/src/cli/runtime-cli.ts
@@ -48,7 +48,7 @@ export async function run(
     return;
   }
 
-  if (argv.version == true) {
+  if (argv.version === true) {
     console.log(`v${VERSION}\n`);
     return;
   }
diff --git a/packages/jest-reporters/src/wrapAnsiString.ts b/packages/jest-reporters/src/wrapAnsiString.ts
index 233a53260140..10d77b2f265c 100644
--- a/packages/jest-reporters/src/wrapAnsiString.ts
+++ b/packages/jest-reporters/src/wrapAnsiString.ts
@@ -24,14 +24,14 @@ export default function wrapAnsiString(
   while ((match = ANSI_REGEXP.exec(string))) {
     const ansi = match[0];
     const index = match.index;
-    if (index != lastIndex) {
+    if (index !== lastIndex) {
       tokens.push(['string', string.slice(lastIndex, index)]);
     }
     tokens.push(['ansi', ansi]);
     lastIndex = index + ansi.length;
   }
 
-  if (lastIndex != string.length - 1) {
+  if (lastIndex !== string.length - 1) {
     tokens.push(['string', string.slice(lastIndex, string.length)]);
   }
 
diff --git a/packages/jest-test-sequencer/src/index.ts b/packages/jest-test-sequencer/src/index.ts
index a0604eddc599..96e95035180c 100644
--- a/packages/jest-test-sequencer/src/index.ts
+++ b/packages/jest-test-sequencer/src/index.ts
@@ -202,9 +202,10 @@ export default class TestSequencer {
       const failedA = this.hasFailed(testA);
       const failedB = this.hasFailed(testB);
       const hasTimeA = testA.duration != null;
+      const hasTimeB = testB.duration != null;
       if (failedA !== failedB) {
         return failedA ? -1 : 1;
-      } else if (hasTimeA != (testB.duration != null)) {
+      } else if (hasTimeA !== hasTimeB) {
         // If only one of two tests has timing information, run it last
         return hasTimeA ? 1 : -1;
       } else if (testA.duration != null && testB.duration != null) {
diff --git a/website/versioned_docs/version-29.4/ExpectAPI.md b/website/versioned_docs/version-29.4/ExpectAPI.md
index 0e7a7a892799..bc205a987d60 100644
--- a/website/versioned_docs/version-29.4/ExpectAPI.md
+++ b/website/versioned_docs/version-29.4/ExpectAPI.md
@@ -811,7 +811,7 @@ For example, let's say that `drinkFlavor` is coded like this:
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -849,7 +849,7 @@ For example, let's say you have a `drinkFlavor` function that throws whenever th
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -1527,7 +1527,7 @@ expect.extend({
 expect.extend({
   async toBeDivisibleByExternalValue(received) {
     const externalValue = await getExternalValueFromRemoteSource();
-    const pass = received % externalValue == 0;
+    const pass = received % externalValue === 0;
     if (pass) {
       return {
         message: () =>
diff --git a/website/versioned_docs/version-29.5/ExpectAPI.md b/website/versioned_docs/version-29.5/ExpectAPI.md
index 0e7a7a892799..bc205a987d60 100644
--- a/website/versioned_docs/version-29.5/ExpectAPI.md
+++ b/website/versioned_docs/version-29.5/ExpectAPI.md
@@ -811,7 +811,7 @@ For example, let's say that `drinkFlavor` is coded like this:
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -849,7 +849,7 @@ For example, let's say you have a `drinkFlavor` function that throws whenever th
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -1527,7 +1527,7 @@ expect.extend({
 expect.extend({
   async toBeDivisibleByExternalValue(received) {
     const externalValue = await getExternalValueFromRemoteSource();
-    const pass = received % externalValue == 0;
+    const pass = received % externalValue === 0;
     if (pass) {
       return {
         message: () =>
diff --git a/website/versioned_docs/version-29.6/ExpectAPI.md b/website/versioned_docs/version-29.6/ExpectAPI.md
index 0e7a7a892799..bc205a987d60 100644
--- a/website/versioned_docs/version-29.6/ExpectAPI.md
+++ b/website/versioned_docs/version-29.6/ExpectAPI.md
@@ -811,7 +811,7 @@ For example, let's say that `drinkFlavor` is coded like this:
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -849,7 +849,7 @@ For example, let's say you have a `drinkFlavor` function that throws whenever th
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -1527,7 +1527,7 @@ expect.extend({
 expect.extend({
   async toBeDivisibleByExternalValue(received) {
     const externalValue = await getExternalValueFromRemoteSource();
-    const pass = received % externalValue == 0;
+    const pass = received % externalValue === 0;
     if (pass) {
       return {
         message: () =>
diff --git a/website/versioned_docs/version-29.7/ExpectAPI.md b/website/versioned_docs/version-29.7/ExpectAPI.md
index 0e7a7a892799..bc205a987d60 100644
--- a/website/versioned_docs/version-29.7/ExpectAPI.md
+++ b/website/versioned_docs/version-29.7/ExpectAPI.md
@@ -811,7 +811,7 @@ For example, let's say that `drinkFlavor` is coded like this:
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -849,7 +849,7 @@ For example, let's say you have a `drinkFlavor` function that throws whenever th
 
 ```js
 function drinkFlavor(flavor) {
-  if (flavor == 'octopus') {
+  if (flavor === 'octopus') {
     throw new DisgustingFlavorError('yuck, octopus flavor');
   }
   // Do some other stuff
@@ -1527,7 +1527,7 @@ expect.extend({
 expect.extend({
   async toBeDivisibleByExternalValue(received) {
     const externalValue = await getExternalValueFromRemoteSource();
-    const pass = received % externalValue == 0;
+    const pass = received % externalValue === 0;
     if (pass) {
       return {
         message: () =>