Why is GAS inputting a invalid range into a data validation? - google-apps-script

Question

function DYNAMIC(){
var s = SpreadsheetApp.getActiveSpreadsheet(), ss = s.getSheetByName("Snippet Gen"),
dd = s.getSheetByName("dv snip"), column = 1, lastc = dd.getLastColumn(),
lastr = dd.getLastRow(), time = ss.getRange(2,1), name = ss.getRange(4,1),
time_v = time.getValue(), tp = dd.getRange(1,1,1,lastc),
nm = dd.getRange(2,column,lastr,1), match = dd.getRange(1,column).getValue();
var rule_tp = SpreadsheetApp.newDataValidation().requireValueInRange(tp,false).build();
time.setDataValidation(rule_tp);
for(; column < lastc; column++){
if(match = time_v){
var rule_nm = SpreadsheetApp.newDataValidation().requireValueInRange(nm,false).build();
name.setDataValidation(rule_nm);
}
}
}
Sheet 1: Snippet Gen
Sheet 2: dv snip
The result is the correct DV in A2 but a continuous Loading… DV in A4. And then when I go into the DV panel, the range is set as 'dv snip'!$A$2:$A$8 which is an invalid range. How do I set the range correctly?

Answer 1

if(match = time_v){ is an assignment not a comparison try this instead if(match == time_v){

Answer 2

You're most probably getting an invalid range because of this method:
nm = dd.getRange(2,column,lastr,1);
Please notice that the method getRange(row, column, numRows, numColumns) takes the number of rows as the third parameter, not the index of the last row in the range.
Because of this, here you are getting a range that:
Starts at row 2.
Its number of rows equals the index of the last row.
With these settings, the last row in this range doesn't exist. Therefore, you get an invalid range.
To fix this, you would have to substract the first row index to the third parameter in the method. One option would define the parameters and the method in this way:
var firstRow = 2;
var column = 1;
var numRows = dd.getLastRow() - firstRow + 1;
var numCols = dd.getLastColumn() - column + 1;
var nm = dd.getRange(firstRow, column, numRows, numCols);
Also, as Cooper said, you should use a comparison operator, not an assignment one in here:
if(match == time_v){
Reference:
getRange(row, column, numRows, numColumns)
Comparison operator
I hope this is of any help.