Comment 22 for bug 1733666

ECMAScript 2017 support including arrow functions are targeted for Qt 5.12, which will be released in November 2018. So I anticipate distributions will be packaging it in spring 2019 (for Fedora, this would be Fedora 30). I propose we start working on migrating to QJSEngine now and try using Function.prototype.bind(this) in place of arrow functions. However, it may be a good idea to hold off releasing a new XML-less mapping system and rewriting Components for that until distributions are shipping Qt 5.12.

https://bugreports.qt.io/browse/QTBUG-47735?focusedCommentId=410092&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-410092