Javascript – Find page numbers where given text occurs

This script takes the currently selected text, uses it as a search phrase, loops through all pages, collects the page numbers of those that contain the search phrase, formats the resulting array as "1, 2, 3, 4", prints it on an alert dialog, and copies it into the clipboard, so the user can paste the resulting string where he wants.

Note, I found InDesign's scripting engine to be incompatible with any non-ancient Javascript feature, hence the C-style for loops. InDesign's scripting environment also has something called findText and findGrep, which may have been useful, but I failed to find their documentation and I failed to get them to do what I wanted. Your mileage might vary.

// Used to let the user define what text to search for by selecting text
function getSelectedText() {
    return app.selection[0].contents
}

// Used to give user access to the result of the script via the clipboard
function copyToClipboard(text) {
    var frame = app.activeDocument.pages[0].textFrames.add();
    frame.geometricBounds = [0,0,200,100];
    frame.contents = text;
    frame.parentStory.texts.everyItem().select();
    app.copy();
    $.sleep(300); // just in case
    frame.remove();
}

// Used for deduplicating the results
Array.prototype.contains = function(obj) {
    var i = this.length;
    while (i--) {
        if (this[i] === obj) {
            return true;
        }
    }
    return false;
}

// Given a targetPhrase, returns an array containing every page number it
// occurs in, in ascending order.
function findPageNumbersOfOccurancesOfText(targetPhrase) {
  // Create an array to store results
  var results = [];
  // Loop through each spread in the document
  for (var s = 0; s < app.activeDocument.spreads.length; s++) {
      var spread = app.activeDocument.spreads[s];
      
      // Loop through each page within the spread
      for (var p = 0; p < spread.pages.length; p++) {
          var page = spread.pages[p];
          
          // Loop through all text frames on the page
          for (var i = 0; i < page.textFrames.length; i++) {
              var textFrame = page.textFrames[i];

              // Check if the target phrase exists in the content of the
              // text frame
              if (textFrame.contents.indexOf(targetPhrase) !== -1) {
                  // The phrase exists in this text frame
                  pageNumber = page.name
                  // Make sure the result array does not contain duplicates
                  if (!results.contains(pageNumber)) {
                      results.push(pageNumber)
                  }
              }
          }
      }
  }
}


// The phrase we're searching for is defined as whatever the user has selected
var targetPhrase = getSelectedText();

var results = findPageNumbersOfOccurancesOfText(targetPhrase);

// Format the result array as something like `1, 2, 3, 4`
var resultsJoined = results.join(', ')

// Print the formatted results on an alert dialog, for instant feedback
alert(resultsJoined)

// Copy the formatted results into clipboard, so that the user can paste it
// where he needs it
copyToClipboard(resultsJoined)