Recently a potential employer posted a Job on odesk, wanted a script to clear the Google Spreadsheet content daily using Google Spreadsheet PHP API. I told him about Google Apps Script, and how we can use it to achieve this as using PHP API wasn't a requirement.

Using Google Apps Script we can clear the content of the Google Spreadsheet daily or on specific time of the day.

1) Open the spreadsheet and click Tools > Script Editor.



2) Copy and Paste the following Google Apps Script

function onOpen() {
var ss = SpreadsheetApp.getActiveSpreadsheet(); // gets opened spreadsheet
var menuEntries = [ {name: "Clear", functionName: "clear"} ]; //adds menu
ss.addMenu("Script", menuEntries); //adds submenu 'Script'
}

function clear() {
var ss = SpreadsheetApp.getActiveSpreadsheet().getSheets(); // get all sheets
ss[0].clear();  //we can set which sheet to clear
}

Save and give relevant name to the script.

3) Set Trigger to execute the 'clear' function at midnight  
    Triggers > Current Scripts Trigger > Add New


This script also adds a new menu to toolbar, Scripts > Clear
We can set different type of triggers, for more read script guide.

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P.S. Tad, Enjoy!