Enable unicorn/prefer-string-slice (#7251)

.eslintrc.yml

@@ -58,6 +58,7 @@ rules:
     - exceptRange: true
   unicorn/new-for-builtins: error
   unicorn/prefer-includes: error
+  unicorn/prefer-string-slice: error
 overrides:
   - files:
       - scripts/**/*.js

scripts/build/babel-plugins/transform-custom-require.js

@@ -22,7 +22,7 @@ module.exports = function(babel) {
         if (isEvalRequire(node.callee) && node.arguments.length === 1) {
           let arg = node.arguments[0];
           if (t.isLiteral(arg) && arg.value.startsWith(".")) {
-            const value = "." + arg.value.substring(arg.value.lastIndexOf("/"));
+            const value = "." + arg.value.slice(arg.value.lastIndexOf("/"));
             arg = t.stringLiteral(value);
           }
           path.replaceWith(t.callExpression(t.identifier("require"), [arg]));

src/language-css/parser-postcss.js

@@ -356,7 +356,7 @@ function parseNestedCSS(node, options) {
       const defaultSCSSDirectiveIndex = value.match(DEFAULT_SCSS_DIRECTIVE);
 
       if (defaultSCSSDirectiveIndex) {
-        value = value.substring(0, defaultSCSSDirectiveIndex.index);
+        value = value.slice(0, defaultSCSSDirectiveIndex.index);
         node.scssDefault = true;
 
         if (defaultSCSSDirectiveIndex[0].trim() !== "!default") {
@@ -367,7 +367,7 @@ function parseNestedCSS(node, options) {
       const globalSCSSDirectiveIndex = value.match(GLOBAL_SCSS_DIRECTIVE);
 
       if (globalSCSSDirectiveIndex) {
-        value = value.substring(0, globalSCSSDirectiveIndex.index);
+        value = value.slice(0, globalSCSSDirectiveIndex.index);
         node.scssGlobal = true;
 
         if (globalSCSSDirectiveIndex[0].trim() !== "!global") {
@@ -454,7 +454,7 @@ function parseNestedCSS(node, options) {
         const customSelector = params.match(/:--\S+?\s+/)[0].trim();
 
         node.customSelector = customSelector;
-        node.selector = parseSelector(params.substring(customSelector.length));
+        node.selector = parseSelector(params.slice(customSelector.length));
         delete node.params;
 
         return node;

src/language-js/comments.js

@@ -534,7 +534,7 @@ function handleCommentAfterArrowParams(text, enclosingNode, comment, options) {
   }
 
   const index = getNextNonSpaceNonCommentCharacterIndex(text, comment, options);
-  if (text.substr(index, 2) === "=>") {
+  if (text.slice(index, index + 2) === "=>") {
     addDanglingComment(enclosingNode, comment);
     return true;
   }

src/language-js/needs-parens.js

@@ -525,7 +525,7 @@ function needsParens(path, options) {
         // See corresponding workaround in printer.js case: "Literal"
         ((options.parser !== "typescript" && !parent.directive) ||
           (options.parser === "typescript" &&
-            options.originalText.substr(options.locStart(node) - 1, 1) === "("))
+            options.originalText.charAt(options.locStart(node) - 1) === "("))
       ) {
         // To avoid becoming a directive
         const grandParent = path.getParentNode(1);

src/language-js/printer-estree.js

@@ -835,7 +835,10 @@ function printPathNoParens(path, options, print, args) {
             comment,
             options
           );
-          return options.originalText.substr(nextCharacter, 2) === "=>";
+          return (
+            options.originalText.slice(nextCharacter, nextCharacter + 2) ===
+            "=>"
+          );
         }
       );
       if (dangling) {
@@ -1191,7 +1194,7 @@ function printPathNoParens(path, options, print, args) {
         path.call(print, "callee"),
         optional,
         isIdentifierWithFlowAnnotation
-          ? `/*:: ${n.callee.trailingComments[0].value.substring(2).trim()} */`
+          ? `/*:: ${n.callee.trailingComments[0].value.slice(2).trim()} */`
           : "",
         printFunctionTypeParameters(path, options, print),
         printArgumentsList(path, options, print)
@@ -3034,7 +3037,7 @@ function printPathNoParens(path, options, print, args) {
         value.typeAnnotation &&
         value.typeAnnotation.range &&
         options.originalText
-          .substring(value.typeAnnotation.range[0])
+          .slice(value.typeAnnotation.range[0])
           .match(/^\/\*\s*:/);
       return concat([
         "(",
@@ -3051,13 +3054,13 @@ function printPathNoParens(path, options, print, args) {
     case "TypeParameterInstantiation": {
       const value = path.getValue();
       const commentStart = value.range
-        ? options.originalText.substring(0, value.range[0]).lastIndexOf("/*")
+        ? options.originalText.slice(0, value.range[0]).lastIndexOf("/*")
         : -1;
       // As noted in the TypeCastExpression comments above, we're able to use a normal whitespace regex here
       // because we know for sure that this is a type definition.
       const commentSyntax =
         commentStart >= 0 &&
-        options.originalText.substring(commentStart).match(/^\/\*\s*::/);
+        options.originalText.slice(commentStart).match(/^\/\*\s*::/);
       if (commentSyntax) {
         return concat([
           "/*:: ",
@@ -6054,8 +6057,9 @@ function printComment(commentPath, options) {
         return printed;
       }
 
+      const commentEnd = options.locEnd(comment);
       const isInsideFlowComment =
-        options.originalText.substr(options.locEnd(comment) - 3, 3) === "*-/";
+        options.originalText.slice(commentEnd - 3, commentEnd) === "*-/";
 
       return "/*" + comment.value + (isInsideFlowComment ? "*-/" : "*/");
     }

src/language-js/utils.js

@@ -645,7 +645,9 @@ function isLastStatement(path) {
 function isFlowAnnotationComment(text, typeAnnotation, options) {
   const start = options.locStart(typeAnnotation);
   const end = skipWhitespace(text, options.locEnd(typeAnnotation));
-  return text.substr(start, 2) === "/*" && text.substr(end, 2) === "*/";
+  return (
+    text.slice(start, start + 2) === "/*" && text.slice(end, end + 2) === "*/"
+  );
 }
 
 function hasLeadingOwnLineComment(text, node, options) {

src/language-markdown/embed.js

@@ -74,7 +74,7 @@ function embed(path, print, textToDoc, options) {
         language.name.toLowerCase() === lang ||
         (language.aliases && language.aliases.includes(lang)) ||
         (language.extensions &&
-          language.extensions.find(ext => ext.substring(1) === lang))
+          language.extensions.find(ext => ext === `.${lang}`))
     );
     if (language) {
       return language.parsers[0];

src/main/core.js

@@ -321,7 +321,7 @@ function format(text, opts) {
 
   const hasUnicodeBOM = text.charCodeAt(0) === UTF8BOM;
   if (hasUnicodeBOM) {
-    text = text.substring(1);
+    text = text.slice(1);
     if (hasCursor) {
       opts.cursorOffset++;
     }

website/static/landing.js

@@ -2,7 +2,7 @@
 
 /* eslint-env browser */
 
-if (location.hash.substring(1).startsWith(encodeURIComponent("{"))) {
+if (location.hash.slice(1).startsWith(encodeURIComponent("{"))) {
   location.pathname = "/playground/";
 }