google-apps-script formatting google-docs

How to write a Google Apps Script function to find and format a specific character throughout a doc?

I'm using docs to save ASCII drawings for a project, and to make it more readable I need the % character to always be gray. However, manually formatting each % would take forever. I suspect I'll need to use a regular expression to locate all of the %, but as an amateur programmer I'm not sure how to write the actual function.

In short, the function needs to:

Find all % characters.
Change text color to gray (#cccccc).

The function only needs to be executed once (not constantly in the background).

Thank you for your help!

I've checked the documentation here: https://developers.google.com/apps-script/guides/docs, but I wasn't able to figure out how to find and format specific text.

Solution

I've created a simple example of how to color the %. This runs from a new menu item and can be run any time.

function onOpen() {
  let ui = DocumentApp.getUi();
  let menu = ui.createMenu("My Menu");
  menu.addItem("Change %","changeColor");
  menu.addToUi();
}

function changeColor() {
  try {
    let doc = DocumentApp.getActiveDocument();
    let body = doc.getBody();
    let range = body.findText("%");
    while( range ) {
      let text = range.getElement().asText();
      if( range.isPartial() ) {
        let start = range.getStartOffset();
        let end = range.getEndOffsetInclusive();
        text.setForegroundColor(start,end,"#cccccc");
      }
      else {
        text.setForegroundColor("#cccccc");
      }
      range = body.findText("%",range);
    }
  }
  catch(err){
    console.log("Error in changeColor: "+err);
  }
}

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