docs: replace var with let and const in rule example (#19302)

* docs: replace var with let and const

* replace more var in no-func-assign

docs/src/rules/no-ex-assign.md

@@ -40,7 +40,7 @@ Examples of **correct** code for this rule:
 try {
     // code
 } catch (e) {
-    var foo = 10;
+    const foo = 10;
 }
 ```
 

docs/src/rules/no-func-assign.md

@@ -6,7 +6,7 @@ handled_by_typescript: true
 
 
 
-JavaScript functions can be written as a FunctionDeclaration `function foo() { ... }` or as a FunctionExpression `var foo = function() { ... };`. While a JavaScript interpreter might tolerate it, overwriting/reassigning a function written as a FunctionDeclaration is often indicative of a mistake or issue.
+JavaScript functions can be written as a FunctionDeclaration `function foo() { ... }` or as a FunctionExpression `const foo = function() { ... };`. While a JavaScript interpreter might tolerate it, overwriting/reassigning a function written as a FunctionDeclaration is often indicative of a mistake or issue.
 
 ```js
 function foo() {}
@@ -31,7 +31,7 @@ function baz() {
     baz = bar;
 }
 
-var a = function hello() {
+let a = function hello() {
   hello = 123;
 };
 ```
@@ -58,15 +58,15 @@ Examples of **correct** code for this rule:
 ```js
 /*eslint no-func-assign: "error"*/
 
-var foo = function () {}
+let foo = function () {}
 foo = bar;
 
 function baz(baz) { // `baz` is shadowed.
     baz = bar;
 }
 
 function qux() {
-    var qux = bar;  // `qux` is shadowed.
+    const qux = bar;  // `qux` is shadowed.
 }
 ```
 

docs/src/rules/no-irregular-whitespace.md

@@ -81,43 +81,43 @@ Examples of **incorrect** code for this rule with the default `{ "skipStrings":
 ```js
 /*eslint no-irregular-whitespace: "error"*/
 
-var thing = function() /*<NBSP>*/{
+const thing = function() /*<NBSP>*/{
     return 'test';
 }
 
-var thing = function( /*<NBSP>*/){
+const foo = function( /*<NBSP>*/){
     return 'test';
 }
 
-var thing = function /*<NBSP>*/(){
+const bar = function /*<NBSP>*/(){
     return 'test';
 }
 
-var thing = function /*<Ogham Space Mark>*/(){
+const baz = function /*<Ogham Space Mark>*/(){
     return 'test';
 }
 
-var thing = function() {
+const qux = function() {
     return 'test'; /*<ENSP>*/
 }
 
-var thing = function() {
+const quux = function() {
     return 'test'; /*<NBSP>*/
 }
 
-var thing = function() {
+const item = function() {
     // Description <NBSP>: some descriptive text
 }
 
 /*
 Description <NBSP>: some descriptive text
 */
 
-var thing = function() {
+const func = function() {
     return / <NBSP>regexp/;
 }
 
-var thing = function() {
+const myFunc = function() {
     return `template <NBSP>string`;
 }
 ```
@@ -131,15 +131,15 @@ Examples of **correct** code for this rule with the default `{ "skipStrings": tr
 ```js
 /*eslint no-irregular-whitespace: "error"*/
 
-var thing = function() {
+const thing = function() {
     return ' <NBSP>thing';
 }
 
-var thing = function() {
+const foo = function() {
     return '​<ZWSP>thing';
 }
 
-var thing = function() {
+const bar = function() {
     return 'th <NBSP>ing';
 }
 ```

docs/src/rules/no-new-native-nonconstructor.md

@@ -16,10 +16,10 @@ It is a convention in JavaScript that global variables beginning with an upperca
 
 ```js
 // throws a TypeError
-let foo = new Symbol("foo");
+const foo = new Symbol("foo");
 
 // throws a TypeError
-let result = new BigInt(9007199254740991);
+const result = new BigInt(9007199254740991);
 ```
 
 Both `new Symbol` and `new BigInt` throw a type error because they are functions and not classes. It is easy to make this mistake by assuming the uppercase letters indicate classes.
@@ -40,8 +40,8 @@ Examples of **incorrect** code for this rule:
 ```js
 /*eslint no-new-native-nonconstructor: "error"*/
 
-var foo = new Symbol('foo');
-var bar = new BigInt(9007199254740991);
+const foo = new Symbol('foo');
+const bar = new BigInt(9007199254740991);
 ```
 
 :::
@@ -53,8 +53,8 @@ Examples of **correct** code for this rule:
 ```js
 /*eslint no-new-native-nonconstructor: "error"*/
 
-var foo = Symbol('foo');
-var bar = BigInt(9007199254740991);
+const foo = Symbol('foo');
+const bar = BigInt(9007199254740991);
 
 // Ignores shadowed Symbol.
 function baz(Symbol) {

docs/src/rules/no-obj-calls.md

@@ -39,25 +39,25 @@ Examples of **incorrect** code for this rule:
 ```js
 /*eslint no-obj-calls: "error"*/
 
-var math = Math();
+const math = Math();
 
-var newMath = new Math();
+const newMath = new Math();
 
-var json = JSON();
+const json = JSON();
 
-var newJSON = new JSON();
+const newJSON = new JSON();
 
-var reflect = Reflect();
+const reflect = Reflect();
 
-var newReflect = new Reflect();
+const newReflect = new Reflect();
 
-var atomics = Atomics();
+const atomics = Atomics();
 
-var newAtomics = new Atomics();
+const newAtomics = new Atomics();
 
-var intl = Intl();
+const intl = Intl();
 
-var newIntl = new Intl();
+const newIntl = new Intl();
 ```
 
 :::
@@ -73,13 +73,13 @@ function area(r) {
     return Math.PI * r * r;
 }
 
-var object = JSON.parse("{}");
+const object = JSON.parse("{}");
 
-var value = Reflect.get({ x: 1, y: 2 }, "x");
+const value = Reflect.get({ x: 1, y: 2 }, "x");
 
-var first = Atomics.load(foo, 0);
+const first = Atomics.load(foo, 0);
 
-var segmenterFr = new Intl.Segmenter("fr", { granularity: "word" });
+const segmenterFr = new Intl.Segmenter("fr", { granularity: "word" });
 ```
 
 :::