Accessing Javascript/Google Apps Script properties via Object.keys TypeError

Question

I'm trying to write a generic script to loop thru an array of objects and return the values of the properties at each cycle. Rather than access the properties via

myArray[0].someProperty;
myArray[0].anotherProperty;

I'm storing property names in an array using Object.keys(myArray[0]). However at runtime I get TypeErrors. Could anyone tell me what I'm doing wrong? Or is there a way I can find out more on what TypeError means in this context? My sample code is below:

// Film Class
function Film(title, year, genre)
{
  this.title = title;
  this.year = year;
  this.genre = genre;
}

function Main()
{
  var films = [];

  films.push(new Film("Furious Seven", 2015, "Action"));
  films.push(new Film("The Matrix", 1999, "Sci Fi"));
  films.push(new Film("Invictus", 2009, "Drama"));

  var headers = Object.keys(films[0]);

  Logger.log(headers[0]);          // title
  Logger.log(films[0].title);      // Furious Seven
  Logger.log(films[0].headers[0]); // TypeError: Cannot read property "0" from undefined.
  Logger.log(films[0].(headers[0])); // TypeError: [object Object] is not an XML object.
}

ScampMichael · Accepted Answer · 2015-05-13 15:02:38Z

1

When trying to extract the value of an object's property using a variable to reference the property's key, the variable representing the key should be enclosed in square brackets without the dot

Logger.log(films[0][headers[0]]);

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_Accessors

edited May 13, 2015 at 15:02

answered May 13, 2015 at 14:23

ScampMichael

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1 Comment

onji Over a year ago

Ahah. Ok I've never seen bracket notation in any languages before. Thanks for the solution + documentation ScampMichael

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