check if each value in array matches any value in another array using indexOf in google apps scripts

Question

Not sure what I'm doing wrong.

function ccheck(){
  var tkhContacts = SpreadsheetApp.openById('##').getSheetByName('contacts');
  var emf = ContactsApp.getContactGroup('emf').getContacts(); 
  var fullNames = emf.map( function(contact){ return contact.getFullName() } );
  var tkhContacts = tkhContacts.getRange('B2:B').getValues();

   for(var i=0;i<fullNames.length;i++){
         if(fullNames[i].indexOf(tkhContacts) == -1){
       Logger.log('missing')}
     }
   }

Trying to put all Google contacts in group 'emf' into an array. Then taking contact names stored in column B in sheet and putting that in an array. Then take each name in the 'fullNames' array and check if it matches any of the names in 'tkhContacts' from the sheet. If a name in 'fullNames' does not match any name in 'tkhContacts' set value as false.

Answer 1

I think that you are using the wrong indexOf method. It looks like you are using the String.prototype.indexOf() rather than Array.prototype.indexOf().

This should work for your code, but it is hard to test without any data.

const a = ['Sally', 'Walker', 'Claire', 'Lilly'];
const b = ['Kyle', 'Sally', 'Walker', 'Caroline', 'Claire'];

const d_hash = {};
const d_list = [];

a.forEach(a => {
  const i = b.indexOf(a);
  if (i === -1) {
    // the name is missing
    d_hash[a] = {
      status: 'missing',
      index: null
    };
    d_list.push(a);
  } else {
    // the name has been found
    d_hash[a] = {
      status: 'found',
      index: i
    }
  }
});

console.log(d_hash);
console.log(d_list);

The logic:

• I have two arrays of names, array a and array b. I want to find the names that appear in a but not in b.
• For each value of a, try to find the index of the element in b. If the index is -1, we know the element could not be found.
• Store the results as a hash and also the list of names that could not be found in an array.
• JS Bin

Alternatively

What you are really wanting the do is find the difference of Set a and Set b.

• A Set is a data structure that contains many elements and an element can only appear once it each set.
• And a difference is also known as find the complement of a set.

We can convert each array to a set and then perform a difference to get the elements that appear in one but not the other.

const a = ['Sally', 'Walker', 'Claire', 'Lilly'];
const b = ['Kyle', 'Sally', 'Walker', 'Caroline', 'Claire'];

const set_a = new Set(a);
const set_b = new Set(b);

// code adapted from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set
Set.prototype.diff = function (b) {
  const d = new Set(a);
  b.forEach(el => d.delete(el));
  return d;
}

console.log(Array.from(set_a.diff(set_b))); // ["Lilly"]

Clarifications:

• What is forEach?

For each is a method natively provided on the Array.prototype in newer browsers. More info here.

forEach should be applied to an array, and the method expects a function callback that should handle each element.

• What is (...) => { ... } ?

This represents arrow functions which are available in ES6. This arrow syntax provides an alternative (and in my opinion, cleaner and clearer) way to define functions.

Something that which was previously represented as:

function (el) {
  d.delete(el);
}

Can be shortened to

(el) => d.delete(el);