excel reading javascript code is hanging

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Javascript

I wrote the javascript code for reading excel sheet and it was running well for excel sheet having 30 rows values but i tried to run excel sheet having approximately 3500 rows values so it becomes hang even output page couldn't been canceled.Although i have not set any limit for array size but why its hanging?
Please can anyone help me to resolve it.

var Excel;
Excel = new ActiveXObject("Excel.Application");
Excel.Visible = false;
var a=Excel.Workbooks.Open("C:/desktop/info.xlsx").sheets(1);
for(var r=1;r<=a.usedrange.rows.count;r++)
{
abc[r-1]=new Array()
for(var c=1;c<=a.usedrange.columns.count;c++)
abc[r-1][c-1]=a.Cells(r,c).Value;
}