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feat(minifier): compress new Array(2) -> [,,] (#8344)

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For an integer value `n` smaller than 6, `Array(n)` can be compressed to `[,,]` (the number of `,` is `n`).
This commit is contained in:
sapphi-red 2025-01-08 12:07:46 +00:00
parent 819c47536c
commit a69d15f299
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GPG key ID: 67631A259A77AC6C
2 changed files with 22 additions and 3 deletions
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21
crates/oxc_minifier/src/ast_passes/peephole_substitute_alternate_syntax.rs
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@ -762,7 +762,24 @@ impl<'a, 'b> PeepholeSubstituteAlternateSyntax {
Some(ctx.ast.expression_array(span, ctx.ast.vec(), None))
}
// `new Array(8)` -> `Array(8)`
else if let Expression::NumericLiteral(_) = arg {
else if let Expression::NumericLiteral(n) = arg {
// new Array(2) -> `[,,]`
// this does not work with IE8 and below
// learned from https://github.com/babel/minify/pull/45
#[expect(clippy::cast_possible_truncation)]
if n.value.fract() == 0.0 {
let n_int = n.value as i64;
if (1..=6).contains(&n_int) {
return Some(ctx.ast.expression_array(
span,
ctx.ast.vec_from_iter((0..n_int).map(|_| {
ArrayExpressionElement::Elision(Elision { span: SPAN })
})),
None,
));
}
}
let callee = ctx.ast.expression_identifier_reference(SPAN, "Array");
let args = ctx.ast.move_vec(args);
Some(ctx.ast.expression_call(span, callee, NONE, args, false))
@ -1143,6 +1160,8 @@ mod test {
// One argument
test("x = new Array(0)", "x = []");
test("x = new Array(\"a\")", "x = [\"a\"]");
test("x = new Array(1)", "x = [,]");
test("x = new Array(6)", "x = [,,,,,,]");
test("x = new Array(7)", "x = Array(7)");
test("x = new Array(7n)", "x = [7n]");
test("x = new Array(y)", "x = Array(y)");

4
tasks/minsize/minsize.snap
View file

@ -11,7 +11,7 @@ Original | minified | minified | gzip | gzip | Fixture
544.10 kB | 71.75 kB | 72.48 kB | 26.16 kB | 26.20 kB | lodash.js
555.77 kB | 272.91 kB | 270.13 kB | 90.92 kB | 90.80 kB | d3.js
555.77 kB | 272.82 kB | 270.13 kB | 90.92 kB | 90.80 kB | d3.js
1.01 MB | 460.22 kB | 458.89 kB | 126.83 kB | 126.71 kB | bundle.min.js
@ -23,5 +23,5 @@ Original | minified | minified | gzip | gzip | Fixture
6.69 MB | 2.32 MB | 2.31 MB | 492.72 kB | 488.28 kB | antd.js
10.95 MB | 3.50 MB | 3.49 MB | 908.29 kB | 915.50 kB | typescript.js
10.95 MB | 3.50 MB | 3.49 MB | 908.28 kB | 915.50 kB | typescript.js