If a column has any cell with a color, change the entire row of that column to that same color, Google Sheets

I've been trying to find out how to do this all day and I tried, everything. I have a Column that has some cells with a background color (Column B.) The sheet has 600 Rows, so Column B goes down to B600, and has columns from A-H. Let's say random rows in B have a color (only one color, let's say blue), let's say cells B4, B7, B11 have a Blue background color. I'm trying to find a way to make it so that the entire row of cells B4, B7, B11 also become Blue. I'd do it manually, but I have a lot of projects like this coming up, and it's not just those 3 rows, it's 100+ cells in that column that have a color.

I've tried setting the range to A1:H6 in conditional formatting, and choosing the "custom formula is" option and set it to:

=OR(ISCOLOR(B1:B600))

I tried other ways as well, one of which is using this:

=OR(B1=0000FF and giving it different ranges like b1:b600

Any help with trying to make this work?

Solution

A sheet has a data range of A1:H600. Some "random" cells in Column B have a "blue" background colour ("#0000ff"). For those cells, it is necessary to set the background colour for the entire row to "blue".

Try this script:

The code gets the background colour for the cells in Column B
It tests the background colour for each cell in Column B (from row 1 to row 600) equals "blue"
If yes, the it sets the background colour of the whole row (A:H)

function setRowColors() {
  var ss = SpreadsheetApp.getActiveSpreadsheet()
  var sheet = ss.getSheetByName("Sheet1")
  
  // get the background colours in Column B
  var range = sheet.getRange('B1:B600')
  var bgColors = range.getBackgrounds()
  
  // loop though Column B
  for (var i=0;i<bgColors.length;i++){
    // if background colour = Blue, then set the whole row as blue
    if (bgColors[i][0] == "#0000ff"){
      sheet.getRange((i+1),1,1,8).setBackground("#0000ff")
    }
  }
}