List - Conditional formatting for blank text field

[JasonC4]

I'm using Lists via Teams (Office 365). I've got a list with a "single line text" column. I'd like to add some conditional formatting if the column contents are not blank.

The only options I see in the conditional formatting dialog are "is equal to" and "is not equal to", so I picked "is not equal to", but it won't accept an empty value in the "choose a type or value" box (which is a plain text field, it's not a dropdown). I tried empty single quotes and empty double quotes but that didn't work.

How do I do this?

Thanks!!

[#2 · Accepted solution]

@JasonC4 

You might want to open the 'Advanced mode' linked at the very bottom above the save button.
In here the operand accepts double quotes for 'blank fields' (line 18).

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "style": {
    "box-sizing": "border-box",
    "padding": "0 2px",
    "overflow": "hidden",
    "text-overflow": "ellipsis"
  },
  "attributes": {
    "class": {
      "operator": ":",
      "operands": [
        {
          "operator": "==",
          "operands": [
            "[$SingleLineOfText]",
            ""
          ]
        },
        "sp-css-backgroundColor-BgGold",
        ""
      ]
    }
  },
  "txtContent": "[$SingleLineOfText]"
}