title: How to pause App Scripts until spreadsheet finishes calculation
body: <p>Because google spreadsheets does not support iterations, I wrote my own simple app script to adjust an input based upon the calculation of the spreadsheet output. However, after I change the input variable, the spreadsheet recalculates but app scripts does not seem to wait for that recalculation so I end up retrieving values such as "Thinking..." or "#NA". Is there a way to pause a script and wait for the calculation to complete before moving to the next line in the script?</p>
  
  <p>Currently, I am just using a loop to watch the cell but I wanted to find out if there was a more elegant way to pause the execution until the sheet was done calculating.</p>
  
  <p>I write a lot of Excel Macros and Excel VBA always waits for the calculation to complete before moving to the next line in the code. Apps Script does not seem to do this so I am hoping there is an easy way to do this. </p>
  
  <p>A second question: Because this iteration can take some time, how does one interrupt and terminate a script from running? I can't seem to find a way to do this.</p>