My csv data looks like this:
heading1,heading2,heading3,heading4,heading5,value1_1,value2_1,value3_1,value4_1,value5_1,value1_2,value2_2,value3_2,val
Per the accepted answer,
I got this to work by changing the 1 to a 0 here:
for (var i=1; i<allTextLines.length; i++) {
changed to
for (var i=0; i<allTextLines.length; i++) {
It will compute the a file with one continuous line as having an allTextLines.length of 1. So if the loop starts at 1 and runs as long as it's less than 1, it never runs. Hence the blank alert box.