react-native .toLocaleString() not working on android

rather than using a polyfill or an external dependency, change the JSC your android app builds with. For the newer versions of react-native add or override the following line in app/build.gradle

def jscFlavor = 'org.webkit:android-jsc-intl:+'

You can use

number.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",")