oxc-project/oxc · error · OxcDiagnostic

Prefer `Date.now()` over `new Date()`

Error message

Prefer `Date.now()` over `new Date()`

What it means

Raised by unicorn/prefer-date-now when `new Date()` is used to obtain the current timestamp. Allocating a Date just for milliseconds is wasteful; the faulting input is the `new Date()` expression at the labeled span, and the fix rewrites it to `Date.now()`.

Source

Thrown at crates/oxc_linter/src/rules/unicorn/prefer_date_now.rs:13

use oxc_ast::{
    AstKind,
    ast::{Argument, Expression},
};
use oxc_diagnostics::OxcDiagnostic;
use oxc_macros::declare_oxc_lint;
use oxc_span::{GetSpan, Span};
use oxc_syntax::operator::{AssignmentOperator, BinaryOperator, UnaryOperator};

use crate::{AstNode, context::LintContext, rule::Rule};

fn prefer_date_now(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("Prefer `Date.now()` over `new Date()`")
        .with_help("Change to `Date.now()`.")
        .with_label(span)
}

fn prefer_date_now_over_methods(span: Span, bad_method: &str) -> OxcDiagnostic {
    OxcDiagnostic::warn(format!("Prefer `Date.now()` over `new Date().{bad_method}()`"))
        .with_help("Change to `Date.now()`.")
        .with_label(span)
}

fn prefer_date_now_over_number_date_object(span: Span, kind: &str) -> OxcDiagnostic {
    OxcDiagnostic::warn(format!("Prefer `Date.now()` over `{kind}(new Date())`"))
        .with_help("Change to `Date.now()`.")
        .with_label(span)
}

#[derive(Debug, Default, Clone)]
pub struct PreferDateNow;

View on GitHub (pinned to e1e7af627c)

Solutions

1. Use `Date.now()` which returns the epoch milliseconds directly
2. If you need a Date object, keep `new Date()` but derive the timestamp via `date.getTime()`

When it happens

Trigger: Thrown at crates/oxc_linter/src/rules/unicorn/prefer_date_now.rs:13 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of oxc-project/oxc@e1e7af627c (2026-08-20). Data as JSON: /api/errors/a3534f3b2e511ea7. Report an issue: GitHub.