jQuery $ > Using a variable (property or object) without declaring it is not allowed in 'strict mode'

using R# 2018.1 I get this warning "Using a variable (property or object) without declaring it is not allowed in 'strict mode'" using this code:

<script type="text/javascript">

"use strict";

$(function() {
$("#UserName").focus();
});

</script>

following this suggestion https://stackoverflow.com/questions/7604419/resharper-javascript-use-of-implicitly-declared-global-variable-x one warning is eliminated and another added. Please see screenshot.