x
<html><body><h2>Оператор += </h2><p id="demo"></p><script>var x = 10;x += 5;document.getElementById("demo").innerHTML = x;</script></body></html><html><body><h2>Оператор += </h2><p id="demo"></p><script>var x = 10;x += 5;document.getElementById("demo").innerHTML = x;</script></body></html>