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fix(linter/prefer-code-point): report String.fromCharCode member references #19931

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Merged
graphite-app merged 1 commit into from
Mar 2, 2026
Merged

fix(linter/prefer-code-point): report String.fromCharCode member references #19931

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2 changes: 1 addition & 1 deletion crates/oxc_linter/src/generated/rule_runner_impls.rs
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41 changes: 28 additions & 13 deletions crates/oxc_linter/src/rules/unicorn/prefer_code_point.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -47,21 +47,31 @@ declare_oxc_lint!(

impl Rule for PreferCodePoint {
fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
let AstKind::CallExpression(call_expr) = node.kind() else {
let AstKind::StaticMemberExpression(member_expr) = node.kind() else {
return;
};

let Some(memb_expr) = call_expr.callee.as_member_expression() else {
return;
};

if memb_expr.is_computed() || memb_expr.optional() || call_expr.optional {
return;
}

let (current, replacement, span) = match memb_expr.static_property_info() {
Some((span, "charCodeAt")) => ("charCodeAt", "codePointAt", span),
Some((span, "fromCharCode")) => ("fromCharCode", "fromCodePoint", span),
let (span, property_name) = member_expr.static_property_info();
let (current, replacement) = match property_name {
"fromCharCode" => {
if !member_expr.object.is_specific_id("String") {
return;
}
("fromCharCode", "fromCodePoint")
}
"charCodeAt" => {
let AstKind::CallExpression(call_expr) = ctx.nodes().parent_kind(node.id()) else {
return;
};
if call_expr.optional
|| call_expr.callee.as_member_expression().and_then(|callee| {
callee.static_property_info().map(|(_, property_name)| property_name)
}) != Some("charCodeAt")
{
return;
}
("charCodeAt", "codePointAt")
}
_ => return,
};

Expand All @@ -82,12 +92,12 @@ fn test() {
"new foo.charCodeAt",
"charCodeAt(0)",
"foo.charCodeAt?.(0)",
"foo?.charCodeAt(0)",
"foo[charCodeAt](0)",
r#"foo["charCodeAt"](0)"#,
"foo.notCharCodeAt(0)",
"String.fromCodePoint(0x1f984)",
"String.fromCodePoint",
"NotString.fromCharCode(foo)",
"new String.fromCodePoint",
"fromCodePoint(foo)",
"String.fromCodePoint?.(foo)",
Expand All @@ -101,9 +111,12 @@ fn test() {

let fail = vec![
"string.charCodeAt(index)",
"string?.charCodeAt(index)",
"(( (( string )).charCodeAt( ((index)), )))",
"String.fromCharCode( code )",
"(( (( String )).fromCharCode( ((code)), ) ))",
"String.fromCharCode.bind(String)",
"const x = String.fromCharCode",
];

let fix = vec![
Expand All @@ -112,6 +125,8 @@ fn test() {
"(( (( String )).fromCharCode( ((code)), ) ))",
"(( (( String )).fromCodePoint( ((code)), ) ))",
),
("String.fromCharCode.bind(String)", "String.fromCodePoint.bind(String)"),
("const x = String.fromCharCode", "const x = String.fromCodePoint"),
(r#""🦄".charCodeAt(0)"#, r#""🦄".codePointAt(0)"#),
("String.fromCharCode(0x1f984);", "String.fromCodePoint(0x1f984);"),
];
Expand Down
21 changes: 21 additions & 0 deletions crates/oxc_linter/src/snapshots/unicorn_prefer_code_point.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,13 @@ source: crates/oxc_linter/src/tester.rs
╰────
help: Unicode is better supported in `codePointAt` than `charCodeAt`

⚠ eslint-plugin-unicorn(prefer-code-point): Prefer `codePointAt` over `charCodeAt`
╭─[prefer_code_point.tsx:1:9]
1 │ string?.charCodeAt(index)
· ──────────
╰────
help: Unicode is better supported in `codePointAt` than `charCodeAt`

⚠ eslint-plugin-unicorn(prefer-code-point): Prefer `codePointAt` over `charCodeAt`
╭─[prefer_code_point.tsx:1:17]
1 │ (( (( string )).charCodeAt( ((index)), )))
Expand All @@ -29,3 +36,17 @@ source: crates/oxc_linter/src/tester.rs
· ────────────
╰────
help: Unicode is better supported in `fromCodePoint` than `fromCharCode`

⚠ eslint-plugin-unicorn(prefer-code-point): Prefer `fromCodePoint` over `fromCharCode`
╭─[prefer_code_point.tsx:1:8]
1 │ String.fromCharCode.bind(String)
· ────────────
╰────
help: Unicode is better supported in `fromCodePoint` than `fromCharCode`

⚠ eslint-plugin-unicorn(prefer-code-point): Prefer `fromCodePoint` over `fromCharCode`
╭─[prefer_code_point.tsx:1:18]
1 │ const x = String.fromCharCode
· ────────────
╰────
help: Unicode is better supported in `fromCodePoint` than `fromCharCode`
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