Use existing spreadsheet formulas in a custom formula in google docs/spreadsheets

Question

I like writing my own formulas inside of Google Docs Spreadsheets. But often what I want to do is very similar to a function that already exists. As an example,

Answer 1

In your custom appscript, you can use the in-built formulas of google spreadsheet in this way:

Lets say you want to use =WEEKDAY() function on cell A1.

Then, get your active spreadsheet like this in your custom appscript function:

var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("YOUR_SHEET_NAME");

now, set the formula like this:

sheet.getRange("A1").setValue("=WEEKDAY()");

Also, if you want to convert 0,1 etc to Sunday,Monday...then define an array like this:

var days = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'];

And then use:

var dayIndex = sheet.getRange("A1").getValue(); 
Logger.log(days[dayIndex]);

You can see the logs using ctrl+enter or by going to View->Logs in script editor itself.