Do you know what may cause memory leaks in JavaScript?

Question

Do you know what may cause memory leaks in JavaScript? I am interested in browsers: IE 7, FireFox 3, Safari 3

Answer 1

In general; circular references are the cause of many problems. I remember IE 6 (not sure if it applies to 7) leaking quite badly with XMLHTTP... setting onreadystatechange = null once it was finished with fixed it.