Return only elements containing specific characters

Question

I need to check each element of an array for a certain letter. if the element contains this letter it should stay within the array, if it does not it should be removed.

currently I'm able to remove elements if they are exact, but not sure how to go about checking each index of each element.

var exampleList = ['alpha', 'beta','dog']

exampleList.filter(function(word) {
    return (word == 'dog');
})

my end goal would be something like this.

letterToInclude = 'a'
var exampleList = ['alpha', 'beta','dog', 'mouse']

exampleList.filter(function(word) {
    return (word == letterToInclude);
})
// returned values = ['alpha', 'beta']

i like `['alpha','beta','dog'].filter(/./.test, RegExp( "a" ));`, but you can write out the functions manually if desired; a lot of people don't understand generic recycling... — dandavis, Jan 17 '17 at 21:18

score 3 · Accepted Answer · answered Jan 17 '17 at 21:15

3

Instead of doing ==, you can use indexOf to see if letterToInclude occurs in word.

letterToInclude = 'a'
var exampleList = ['alpha', 'beta','dog', 'mouse']

exampleList.filter(function(word) {
    return (word.indexOf(letterToInclude) > -1);
});

indexOf returns the position that letterToInclude occurs in word; in the event it is not found, indexOf will return -1.

The reason I didn't use word.includes(letterToInclude) is just for compatibility purposes. includes is fairly new and isn't completely supported.

answered Jan 17 '17 at 21:15

Tyler Roper

21,445
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thanks for the help, I must have been using indexOf wrong prior to this. – Pyreal Jan 17 '17 at 21:25
Would comparing an array of words to include be similar to this? – Pyreal Jan 17 '17 at 21:26
1

A good answer to that question could be found here: http://stackoverflow.com/questions/11076067/finding-matches-between-multiple-javascript-arrays – Tyler Roper Jan 17 '17 at 21:41

Nenad Vracar · Answer 2 · 2017-01-17T21:29:24.337

You can use indexOf() to check if each element contains a specific letter.

var letterToInclude = 'a'
var exampleList = ['alpha', 'beta', 'dog', 'mouse']

exampleList = exampleList.filter(function(word) {
  return word.indexOf(letterToInclude) != -1
})

console.log(exampleList)

ES6 solution with String#includes(), also you can use match() or test() but those take regular expressions.

exampleList.filter(word => word.includes(letterToInclude))

score 0 · Answer 3 · answered Jan 17 '17 at 21:16

0

Try using indexOf:

letterToInclude = 'a'
var exampleList = ['alpha', 'beta','dog', 'mouse']

console.log(exampleList.filter(function(word) {
    return ~(word.indexOf(letterToInclude));
}));

answered Jan 17 '17 at 21:16

cyberbit

1,345
15
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score 0 · Answer 4 · answered Jan 17 '17 at 21:23

It works well together with Unicode chars:

var lettersToInclude = 'aa'
var exampleList = ['a', 'aa','❤✓☀a★bAb', 'bbaa', 'aa☂']

var r = exampleList.filter(function(word) {
    return (word.indexOf(lettersToInclude) > -1);
});

console.log(r);

Return only elements containing specific characters

4 Answers4