JS-1113 Fix FP on S7759 for polyfill fallback using Date#getTime() for Date.now()

[ss-vibe-bot]

Summary

Fix false positives in rule S7759 when Date#getTime() or +(new Date()) is used as a polyfill fallback for Date.now(). These patterns are common in legacy code to provide compatibility with older environments that don't support Date.now().

Changes

• Add decorator to detect and suppress reports for legitimate polyfill patterns:
  • Logical OR: Date.now || function() { return new Date().getTime(); }
  • Ternary: Date.now ? Date.now() : +(new Date())
  • IfStatement: if (!Date.now) { Date.now = function() { ... }; }
• Add comprehensive test coverage for polyfill patterns
• Add tests derived from real-world ruling analysis (chained ternary, class static property, export const patterns)
• Sync expected ruling files

Relates to JS-1113

[github-actions]

Ruling Report

Code no longer flagged (10 issues)

S7759

TypeScript/lib/tsc.js:86

    84 | var ts;
    85 | (function (ts) {
>   86 |     ts.timestamp = typeof performance !== "undefined" && performance.now ? function () { return performance.now(); } : Date.now ? Date.now : function () { return +(new Date()); };
    87 | })(ts || (ts = {}));
    88 | (function (ts) {

TypeScript/lib/typingsInstaller.js:96

    94 | var ts;
    95 | (function (ts) {
>   96 |     ts.timestamp = typeof performance !== "undefined" && performance.now ? function () { return performance.now(); } : Date.now ? Date.now : function () { return +(new Date()); };
    97 | })(ts || (ts = {}));
    98 | (function (ts) {

TypeScript/src/compiler/performance.ts:5

     3 |     declare const performance: { now?(): number } | undefined;
     4 |     /** Gets a timestamp with (at least) ms resolution */
>    5 |     export const timestamp = typeof performance !== "undefined" && performance.now ? () => performance.now() : Date.now ? Date.now : () => +(new Date());
     6 | }
     7 | 

ace/lib/ace/mode/javascript/jshint.js:3188

  3186 |   // A (possibly faster) way to get the current timestamp as an integer.
  3187 |   var now = Date.now || function() {
> 3188 |     return new Date().getTime();
  3189 |   };
  3190 | 

ace/tool/perf-test.html:61

    59 |   <script>
    60 |     if (!Date.now) {
>   61 |         Date.now = function() { return (new Date()).getTime() };
    62 |     }
    63 | 

es5-shim/es5-shim.js:1619

  1617 |     if (!Date.now) {
  1618 |         Date.now = function now() {
> 1619 |             return new Date().getTime();
  1620 |         };
  1621 |     }

qunit/src/core/utilities.js:7

     5 | export const hasOwn = Object.prototype.hasOwnProperty;
     6 | export const now = Date.now || function() {
>    7 | 	return new Date().getTime();
     8 | };
     9 | 

qunit/test/autostart.html:16

    14 | 	( function() {
    15 | 		var now = Date.now || function() {
>   16 | 			return new Date().getTime();
    17 | 		};
    18 | 		var asyncDelay = 1000;

rxjs/src/Scheduler.ts:26

    24 | export class Scheduler implements IScheduler {
    25 | 
>   26 |   public static now: () => number = Date.now ? Date.now : () => +new Date();
    27 | 
    28 |   constructor(private SchedulerAction: typeof Action,

underscore/underscore.js:1464

  1462 |   // A (possibly faster) way to get the current timestamp as an integer.
  1463 |   _.now = Date.now || function() {
> 1464 |     return new Date().getTime();
  1465 |   };
  1466 | 

[ss-vibe-bot]

github-actions[bot] 2026-02-05T13:10:39Z addressed
Thanks for the ruling report! These 10 issues are expected to no longer be flagged - they are all polyfill fallback patterns where Date#getTime() or +(new Date()) is used as a fallback when Date.now is not available.

The fix correctly detects and suppresses issues for these patterns:

• Logical OR: Date.now || function() { return new Date().getTime(); }
• Ternary: Date.now ? Date.now : () => +(new Date())
• If-statement: if (!Date.now) { Date.now = function() { ... }; }

All 10 examples in the report match these polyfill patterns and should not be flagged as issues. The expected ruling files have been synced to reflect this change.

[francois-mora-sonarsource]

LGTM

[ss-vibe-bot]

francois-mora-sonarsource 2026-02-06T15:29:59Z addressed
Thanks for the review!

[francois-mora-sonarsource]

LGTM

[sonarqube-next]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0 Dependency risks
90.8% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube