feat(linter) eslint-plugin-unicorn: prefer string slice (#1247)

crates/oxc_linter/src/rules.rs

@@ -173,6 +173,7 @@ mod unicorn {
     pub mod prefer_regexp_test;
     pub mod prefer_spread;
     pub mod prefer_string_replace_all;
+    pub mod prefer_string_slice;
     pub mod prefer_string_starts_ends_with;
     pub mod prefer_string_trim_start_end;
     pub mod prefer_type_error;
@@ -320,8 +321,9 @@ oxc_macros::declare_all_lint_rules! {
     unicorn::prefer_regexp_test,
     unicorn::prefer_spread,
     unicorn::prefer_string_replace_all,
-    unicorn::prefer_string_trim_start_end,
+    unicorn::prefer_string_slice,
     unicorn::prefer_string_starts_ends_with,
+    unicorn::prefer_string_trim_start_end,
     unicorn::prefer_type_error,
     unicorn::require_number_to_fixed_digits_argument,
     unicorn::switch_case_braces,

crates/oxc_linter/src/rules/unicorn/prefer_string_slice.rs

@@ -0,0 +1,127 @@
+use oxc_ast::{ast::MemberExpression, AstKind};
+use oxc_diagnostics::{
+    miette::{self, Diagnostic},
+    thiserror::{self, Error},
+};
+use oxc_macros::declare_oxc_lint;
+use oxc_span::{Atom, Span};
+
+use crate::{context::LintContext, rule::Rule, AstNode};
+
+#[derive(Debug, Error, Diagnostic)]
+#[error("eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#{1}()")]
+#[diagnostic(severity(warning))]
+struct PreferStringSliceDiagnostic(#[label] pub Span, Atom);
+
+#[derive(Debug, Default, Clone)]
+pub struct PreferStringSlice;
+
+declare_oxc_lint!(
+    /// ### What it does
+    ///
+    /// Prefer [`String#slice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice) over [`String#substr()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substr) and [`String#substring()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring).
+    ///
+    /// ### Why is this bad?
+    ///
+    /// [`String#substr()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substr) and [`String#substring()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring) are the two lesser known legacy ways to slice a string. It's better to use [`String#slice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice) as it's a more popular option with clearer behavior that has a consistent [`Array` counterpart](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice).
+    ///
+    /// ### Example
+    /// ```javascript
+    /// ```
+    PreferStringSlice,
+    correctness
+);
+
+impl Rule for PreferStringSlice {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::CallExpression(call_expr) = node.kind() else {
+            return;
+        };
+
+        let Some(member_expr) = call_expr.callee.get_member_expr() else { return };
+
+        let (span, name) = match member_expr {
+            MemberExpression::StaticMemberExpression(v) => {
+                if !matches!(v.property.name.as_str(), "substr" | "substring") {
+                    return;
+                }
+                (v.property.span, &v.property.name)
+            }
+            _ => return,
+        };
+
+        ctx.diagnostic(PreferStringSliceDiagnostic(span, name.clone()));
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        r#"const substr = foo.substr"#,
+        r#"const substring = foo.substring"#,
+        r#"foo.slice()"#,
+        r#"foo.slice(0)"#,
+        r#"foo.slice(1, 2)"#,
+        r#"foo?.slice(1, 2)"#,
+        r#"foo?.slice?.(1, 2)"#,
+        r#"foo?.bar.baz.slice(1, 2)"#,
+        r#"foo.slice(-3, -2)"#,
+    ];
+
+    let fail = vec![
+        r#"foo.substr()"#,
+        r#"foo?.substr()"#,
+        r#"foo.bar?.substring()"#,
+        r#"foo?.[0]?.substring()"#,
+        r#"foo.bar.substr?.()"#,
+        r#"foo.bar?.substring?.()"#,
+        r#"foo.bar?.baz?.substr()"#,
+        r#"foo.bar?.baz.substring()"#,
+        r#"foo.bar.baz?.substr()"#,
+        r#""foo".substr()"#,
+        r#""foo".substr(1)"#,
+        r#""foo".substr(1, 2)"#,
+        r#""foo".substr(bar.length, Math.min(baz, 100))"#,
+        r#""foo".substr(1, length)"#,
+        r#""foo".substr(1, "abc".length)"#,
+        r#""foo".substr("1", 2)"#,
+        r#""foo".substr(0, -1)"#,
+        r#""foo".substr(0, "foo".length)"#,
+        r#""foo".substr(1, length)"#,
+        r#"foo.substr(start)"#,
+        r#""foo".substr(1)"#,
+        r#"foo.substr(start, length)"#,
+        r#""foo".substr(1, 2)"#,
+        r#"foo.substr(1, 2, 3)"#,
+        r#""Sample".substr(0, "Sample".lastIndexOf("/"))"#,
+        r#"foo.substring()"#,
+        r#""foo".substring()"#,
+        r#""foo".substring(1)"#,
+        r#""foo".substring(1, 2)"#,
+        r#""foo".substring(2, 1)"#,
+        r#""foo".substring(-1, -5)"#,
+        r#""foo".substring(-1, 2)"#,
+        r#""foo".substring(length)"#,
+        r#""foobar".substring("foo".length)"#,
+        r#""foo".substring(0, length)"#,
+        r#""foo".substring(length, 0)"#,
+        r#"foo.substring(start)"#,
+        r#""foo".substring(1)"#,
+        r#"foo.substring(start, end)"#,
+        r#""foo".substring(1, 3)"#,
+        r#"foo.substring(1, 2, 3)"#,
+        r#"foo.substr(0, ...bar)"#,
+        r#"foo.substr(...bar)"#,
+        r#"foo.substr(0, (100, 1))"#,
+        r#"foo.substr(0, 1, extraArgument)"#,
+        r#"foo.substr((0, bar.length), (0, baz.length))"#,
+        r#"foo.substring((10, 1), 0)"#,
+        r#"foo.substring(0, (10, 1))"#,
+        r#"foo.substring(0, await 1)"#,
+        r#"foo.substring((10, bar))"#,
+    ];
+
+    Tester::new_without_config(PreferStringSlice::NAME, pass, fail).test_and_snapshot();
+}