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<html><body><h1>JavaScript Arrays</h1><h2>findLastIndex()</h2><p>Click "Test" to return the index of the last array element that has a value above this number:</p><p><input type="number" id="toCheck" value="18"></p><button onclick="myFunction()">Test</button><p id="demo"></p><script>const numbers = [4, 12, 16, 20];function checkValue(x) { return x > document.getElementById("toCheck").value;}function myFunction() { document.getElementById("demo").innerHTML = numbers.findLastIndex(checkValue);}</script><p>findLastIndex() is not supported in Internet Explorer.</p></body></html>