b=10; while(a=b) { b--; if(b==-10)break; } B goes from 10 to -10. In my world, the while-statement, a=b, should always be true (since the assigment always "goes well"). That is not the case. When the loop stops, b will have a value of 0. In my world, it should pass 0 and go all the way to -10, when the if-statement kicks in. Have I misunderstood something major? (Code tested in IE8 and Adobe Acrobat)