Bug 200714 – String.prototype.replace truncates $<number> values

• Component: JavaScriptCore
• Status: RESOLVED INVALID

# Summary

When replacing with a value that contains $<number>, the value is truncated of $ and first number.

# Test

var string = "Get %{amount} credit";
var regex = new RegExp(`%{amount}`, "g");
console.log(string.replace(regex, "$100"));

# Expected

> Get $100 credit

# Actual

> Get 00 credit

This could be related to a non-standard feature: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/n#Examples

[Radar WebKit Bug Importer]

<rdar://problem/54306164>

After further investigation, this issue looks to be caused by an old String.prototype.replace polyfill from core-js@2.0.3.

Ref: https://github.com/zloirock/core-js/blob/v2.0.3/modules/es6.regexp.replace.js