Gradle util to extract react-native version from package.json

readReactNativeVersion.gradle

import groovy.json.JsonSlurper

def readReactNativeVersion(packagejson, section) {
    def packageSlurper = new JsonSlurper()
    def packageJson = packageSlurper.parse file(packagejson)
    return packageJson.get(section).get('react-native')
}

ext {
    readReactNativeVersion = this.&readReactNativeVersion
}