function findText(item) {
  var background = '#' + (Math.random().toString(16) + "000000").substring(2,8)

  Logger.log(item)

  var searchResult

  searchResult = DocumentApp.getActiveDocument().getBody().findText(item)

  Logger.log(searchResult)

  while (searchResult !== null) {

  searchResult.getElement().asText().setBackgroundColor(searchResult.getStartOffset(), searchResult.getEndOffsetInclusive(), background)

  searchResult = DocumentApp.getActiveDocument().getBody().findText(item,searchResult)

  }


}


function highlightProblem(){

  var words = ["very", "so", "totally", "really", "for", "to"]

  words.forEach(findText)

}

function onOpen(){
DocumentApp.getUi().createMenu('Fix your trash').addItem('Highlight_Common_Mistake', 'highlightProblem').addToUi()
}