getSpreadsheetData() utility function takes the name of a worksheet, then grabs all the data on the page and gives you back an array of objects, with the first row as property names.

getSpreadsheetData.js

function getSpreadsheetData(sheetName) {
  // This function gives you an array of objects modeling a worksheet's tabular data, where the first items — column headers — become the property names.
  var arrayOfArrays = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheetName || 'Sheet1').getDataRange().getValues();
  var headers = arrayOfArrays.shift();
  return arrayOfArrays.map(function (row) {
    return row.reduce(function (memo, value, index) {
      if (value) {
        memo[headers[index]] = value;
      }
      return memo;
    }, {});
  });
}