Refactor: substr() is deprecated, using slice() instead

- `substr()` is not part of the core JS since ~2018
- No wonder why no one noticed this :)
- Though its supported by modern browsers, its deprecated
- Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substr

Why `slice()` and not `substring()`?
> Beacuse I like pizza ;) jk

The reason, that I'm not using the most obvious alternative substring() is; it swaps the args passed, when;
`startIndex > endIndex`, which I think is not a property of good fn and also does not reflects in it's name,
and could lead to more bugs in most of the cases
also, it doesn't support negative args, which I think reduces flexibility to work with it.

- Ref: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring#differences_between_substring_and_slice
- `slice`: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice
- `substring`: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring

Author: Pranav-yadav

packages/assets/path-support.js

@@ -82,7 +82,7 @@ function getAndroidResourceIdentifier(asset: PackagerAsset): string {
 
 function getBasePath(asset: PackagerAsset): string {
   const basePath = asset.httpServerLocation;
-  return basePath.startsWith('/') ? basePath.substr(1) : basePath;
+  return basePath.startsWith('/') ? basePath.slice(1) : basePath;
 }
 
 module.exports = {

packages/hermes-inspector-msggen/src/Converters.js

@@ -9,11 +9,11 @@
  */
 
 export function toCppNamespace(domain: string): string {
-  return domain.substr(0, 1).toLowerCase() + domain.substr(1);
+  return domain.slice(0, 1).toLowerCase() + domain.slice(1);
 }
 
 export function toCppType(type: string): string {
-  return type.substr(0, 1).toUpperCase() + type.substr(1);
+  return type.slice(0, 1).toUpperCase() + type.slice(1);
 }
 
 export type JsTypeString =

packages/hermes-inspector-msggen/src/Property.js

@@ -114,8 +114,8 @@ function toDomainAndId(
     domain = curDomain;
     id = absOrRelRef;
   } else {
-    domain = absOrRelRef.substr(0, i);
-    id = absOrRelRef.substr(i + 1);
+    domain = absOrRelRef.slice(0, i);
+    id = absOrRelRef.slice(i + 1);
   }
 
   return [domain, id];

packages/polyfills/console.js

@@ -252,7 +252,7 @@ const inspect = (function () {
                 return '  ' + line;
               })
               .join('\n')
-              .substr(2);
+              .slice(2);
           } else {
             str =
               '\n' +
@@ -274,7 +274,7 @@ const inspect = (function () {
       }
       name = JSON.stringify('' + key);
       if (name.match(/^"([a-zA-Z_][a-zA-Z_0-9]*)"$/)) {
-        name = name.substr(1, name.length - 2);
+        name = name.slice(1, name.length - 2);
         name = ctx.stylize(name, 'name');
       } else {
         name = name

packages/react-native/Libraries/DOM/Nodes/ReadOnlyCharacterData.js

@@ -67,6 +67,6 @@ export default class ReadOnlyCharacterData extends ReadOnlyNode {
       );
     }
     let adjustedCount = count < 0 || count > data.length ? data.length : count;
-    return data.substr(offset, adjustedCount);
+    return data.slice(offset, offset + adjustedCount);
   }
 }

packages/react-native/Libraries/Inspector/NetworkOverlay.js

@@ -64,7 +64,7 @@ function getStringByValue(value: any): string {
   }
   if (typeof value === 'string' && value.length > 500) {
     return String(value)
-      .substr(0, 500)
+      .slice(0, 500)
       .concat('\n***TRUNCATED TO 500 CHARACTERS***');
   }
   return value;

packages/react-native/Libraries/LogBox/UI/AnsiHighlight.js

@@ -73,7 +73,7 @@ export default function Ansi({
       return content.replace(/\| $/, ' ');
     } else if (key === 2 && commonWhitespaceLength < Infinity) {
       // Remove common whitespace at the beginning of the line
-      return content.substr(commonWhitespaceLength);
+      return content.slice(commonWhitespaceLength);
     } else {
       return content;
     }

packages/react-native/Libraries/LogBox/UI/LogBoxMessage.js

@@ -138,25 +138,22 @@ function LogBoxMessage(props: Props): React.Node {
     const key = String(index);
 
     if (substitution.offset > prevOffset) {
-      const prevPart = content.substr(
-        prevOffset,
-        substitution.offset - prevOffset,
-      );
+      const prevPart = content.slice(prevOffset, substitution.offset);
 
       createUnderLength(key, prevPart);
     }
 
-    const substitutionPart = content.substr(
+    const substitutionPart = content.slice(
       substitution.offset,
-      substitution.length,
+      substitution.offset + substitution.length,
     );
 
     createUnderLength(key + '.5', substitutionPart, substitutionStyle);
     return substitution.offset + substitution.length;
   }, 0);
 
   if (lastOffset < content.length) {
-    const lastPart = content.substr(lastOffset);
+    const lastPart = content.slice(lastOffset);
     createUnderLength('-1', lastPart);
   }
 

packages/react-native/Libraries/Utilities/PolyfillFunctions.js

@@ -32,7 +32,7 @@ function polyfillObjectProperty<T>(
 ): void {
   const descriptor = Object.getOwnPropertyDescriptor<$FlowFixMe>(object, name);
   if (__DEV__ && descriptor) {
-    const backupName = `original${name[0].toUpperCase()}${name.substr(1)}`;
+    const backupName = `original${name[0].toUpperCase()}${name.slice(1)}`;
     Object.defineProperty(object, backupName, descriptor);
   }
 

packages/react-native/ReactAndroid/src/androidTest/js/TextInputTestModule.js

@@ -47,7 +47,7 @@ class TokenizedTextExample extends React.Component {
       if (token[0].length === 0) {
         index = 1;
       }
-      parts.push(_text.substr(0, index));
+      parts.push(_text.slice(0, index));
       parts.push(token[0]);
       index = index + token[0].length;
       _text = _text.slice(index);