JavaScript's
eval
function will return the result of the last command executed, in your case it is '0~44'.
So length will 4 - and it is true for all browsers. I run it on IE9, Opera, Firefox, Chrome, IE 11 and Safari - all returns 4!
If you want to create some dynamic array try this:
var cmd = "['19~3','19~4','20~5','20~6','18~8','20~9','19~10','19~11','17~12','19~13','20~14','19~15','18~16','18~17','17~21','20~22','20~16','8~28','15~28','0~31','0~32','0~33','19~23','0~41','1~2','0~42','2~5','6~1','4~1','0~43','0~44']";
var GroupArr = eval(cmd);
alert(GroupArr.length);