Place Holder
If there is no value in the cell, you can display a notice using the Place Holder function. Check the product number column.
var columns = [
...
{
name: "ProductId",
fieldName: "ProductId",
width: "130",
header: {
text: "Product number",
styleName: "orange-column"
},
placeHolder: "Enter the product number.",
//placeHolderStyleName: "pink-cell" //Used when specifying a separate style
},
...
];
gridView.setColumns(columns);