writing a count program to find the number of repeatitions - google-apps-script

Question

I am writing a code to count the number of times a time duration in column B is repeated.After writing a code according to my logic I am still getting error or no output. Here's the app script code I have written. Help me out.
function count() {
var data = SpreadsheetApp.getActive();
var sheet = data.getSheetByName("Sheet4");
var lastRow = sheet.getLastRow();
var sh = sheet.getRange('B1:B' + lastRow);
var cell = sh.getValues();
var count = 0;
for (var i = 0; i < lastRow; j++) {
var column2 = cell[i][1];
for (var j = 0; j < i; j++) {
var column4 = cell[j][1];
if (column4 == column2) {
count++;
}
}
sheet.getRange('F' + (i + 1).toString()).setValue(count);
}
}
This is the intended output instead of column F i put the sample output in column C

Answer 1

Issue(s):
Outer loop's increment variable doesn't change.
for (var i = 0; i < lastRow;/*i never changes =>*/ j++)
Date/Time are retrieved as JavaScript objects and cannot be compared with ==:
if (column4 == column2) {//Date objects cannot be compared
cell doesn't have a value at array index [1]
Solution:
Increment all variables in the for -loop
Compare value of date objects instead
Array indexes start at [0]
Snippet:
for (var i = 0; i < lastRow; ++i) {
var column2 = cell[i][0];
/*....*/
var column4 = cell[j][0];
if (column4 - column2 === 0) {//#see https://stackoverflow.com/questions/492994