Apps script: filter out empty elements from array

Question

I have the following function:

  var rows = sheet2Json(sheet);

  var emails = rows.filter(function (el) { //ONLY CHECKED ROWS.
         return el != "";
    })
               .map(function (row) { //ONLY CHECKED ROWS.
      return row['EMAIL'];
    });  



  Logger.log(emails)
  return (emails);
}

rows produces the sheet in an array of objects that looks like:

[{ EMAIL=xxx,  TEMPLATE=CONSULT, Index=Thu Jan 24 16:26:02 GMT-05:00 2019 }
...
]

I want an array of all the emails filtering out the empty rows. With the code above I'm getting:

[ [email protected], [email protected],  , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ]

How can I get rid of the empty rows?

jo_va · Accepted Answer · 2019-03-08 07:13:13Z

2

You have to get the EMAIL property first, then filter the entries which are empty or undefined:

var rows = [
  { EMAIL: '[email protected]', prop: 'bla' },
  { EMAIL: '', prop: 'bla' },
  { EMAIL: undefined },
  { EMAIL: '[email protected]', prop: 'bla' },
  { },
  undefined
];

var emails = rows
  .map(function (row) { return row && row.EMAIL; })
  .filter(Boolean);

console.log(emails);

The reason it's not working the other way is that you need to filter out the empty EMAIL fields, but you are filtering rows by comparing them to an empty string. An empty row ({}) will not pass your filter test.

To make it work the other way, you need to filter the rows based on their EMAIL property first, then map:

var rows = [
  { EMAIL: '[email protected]', prop: 'bla' },
  { EMAIL: '', prop: 'bla' },
  { EMAIL: undefined },
  { EMAIL: '[email protected]', prop: 'bla' },
  { },
  undefined
];

var emails = rows
  .filter(function (row) { return row && row.EMAIL; })
  .map(function (row) { return row.EMAIL; });

console.log(emails);

edited Mar 8, 2019 at 7:13

answered Mar 7, 2019 at 22:49

jo_va

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4 Comments

user1592380 Over a year ago

Apps Script is basically JS 1.6. No includes, no let, no iterators, no arrow syntax. It does have map, filter, reduce, some, and every support.

jo_va Over a year ago

@user61629, I updated the answer and added more explanations

user1592380 Over a year ago

regarding "return row && row.EMAIL;" - I'm assuming that means if row exists return row.Email ?

jo_va Over a year ago

@user61629, Yes you are right, if row is falsy, the right most expression is not evaulated and undefined is returned

Tanaike · Accepted Answer · 2019-03-07 23:01:35Z

2

You want to retrieve the values of EMAIL from the object like [{ EMAIL=xxx, TEMPLATE=CONSULT, Index=Thu Jan 24 16:26:02 GMT-05:00 2019 }...] using Google Apps Script.

If my understanding is correct, How about this modification? In this modification, I used reduce(). Please think of this as just one of several answers.

Modified script:

var emails = rows.reduce(function (ar, row) {
  row['EMAIL'] && ar.push(row['EMAIL']);
  return ar;
}, []);

Reference:

reduce()

answered Mar 7, 2019 at 23:01

Tanaike

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3 Comments

user1592380 Over a year ago

Thank you! its a great example!

user1592380 Over a year ago

regarding "row['EMAIL'] && ar.push(row['EMAIL']" - does this mean "if email exists push it to the accumulator array" ?

Tanaike Over a year ago

@user61629 Yes. That's right. Also, By putting row['EMAIL'] before ar.push(row['EMAIL']), at first, row['EMAIL'] is compared.

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