Custom Google sheets script for highlighting my & my friends movie ratings

OpinionHighlighter.gs

// The columns that will contain opinions (emoji).
const opinionColumns = [16, 17, 18, 19, 20];

// The columns to change the colour of.
const toColourColumns = [15, 16, 17, 18, 19, 20];

// The weights given to each individual opinion.
const opinionWeights = {
    "😍": 6,
    "👍": 3,
    "🤔": 1,
    "😤": 0
};

// The colours to use.
// The number of colours must match up to all possible opinion averages (the opinion avg is rounded).
const opinionAvgColours = [
    "#ffffff", // 0
    "#ffffff", // 1
    "#ffffff", // 2
    "#c7f0c7", // 3
    "#87e187", // 4
    "#228B22", // 5
    "#39ff14"  // 6
];

// The row that the reviews start on.
const startingRow = 7;

// Update the colour for a specific row.
// Returns the opinion average for the row.
function updateRowColour(sheet, rowNum) {
    const opinionCells = sheet.getRange(rowNum, opinionColumns[0], 1, opinionColumns.length);

    let opinionTotal = 0;
    let opinionCount = 0;
    const values = opinionCells.getValues()[0];

    values.forEach((val) => {
        if (val in opinionWeights) {
            opinionCount += 1;
            opinionTotal += opinionWeights[val];
        }
    });

    const toColourCells = sheet.getRange(rowNum, toColourColumns[0], 1, toColourColumns.length);
    const opinionAvg = Math.round(opinionTotal / opinionCount);

    toColourCells.setBackground(opinionAvgColours[opinionAvg]);

    return opinionTotal;
}

// Run whenever an edit is made to the sheet.
function onEdit(e) {
    // Will only edit colours if the left most edited cell is within the toColourColumns range.
    if (e.range.getRow() >= startingRow && toColourColumns.includes(e.range.getColumn())) {
        const sheet = SpreadsheetApp.getActiveSheet();
        updateRowColour(sheet, e.range.getRow());
    }
}

// Iterates over all rows and updates the colours.
// If 3 rows with an opinion avg of 0 occur one after the other it stops (prevents it going on forever).
function updateAllColours() {
    const sheet = SpreadsheetApp.getActiveSheet();

    blankRows = 0;
    currentRow = startingRow;

    while (blankRows <= 3) {
        const rowOpinionAvg = updateRowColour(sheet, currentRow);
        if (rowOpinionAvg == 0) {
            blankRows += 1
        } else {
            blankRows = 0
        }
        currentRow += 1;
    }
}