javascript array | return an index if value contains a string

Question

I have an array of strings stringsArr and also I have a string myString. I would like to find first index of my array for which value is euqal myString OR contains myString.

I know method indexOf(), but unfortunatelly it works only if value equals myString. I googled through documentation, but didn't find anything suitable, so decided to ask here if I didn't miss something.

ssube · Accepted Answer · 2016-03-14 16:05:11Z

4

You want to use findIndex and a custom predicate like:

stringsArr.findIndex(function (str) {
  return (str === myString || str.indexOf(myString) > -1);
});

If you're using an environment(/browser) that doesn't provide findIndex, the MDN page includes a nice short polyfill.

edited Mar 14, 2016 at 16:05

answered Mar 14, 2016 at 16:01

ssube

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4 Comments

Shulyk Volodymyr Over a year ago

You've forgot to mention - es2015.

Isla Over a year ago

Nice solution, but still does not work for too many browsers :) Next project will write with babel, so will use it for sure

ssube Over a year ago

@Kania check the MDN page for a polyfill. You can add findIndex to all the current browsers and use it today.

Isla Over a year ago

Unfortunately in existing code adding polyfills is not an option :D looking forward for new project! Thanks for showing this solution!

cwallenpoole · Accepted Answer · 2016-03-14 16:03:35Z

1

indexOf is probably what you want, but using indexOf on the String:

var tested = ['foot','bark', 'foo','cat'];
var match = 'foo';
for(var i = 0; i < tested.length; i++)
    if(tested[i].indexOf(match) > -1) console.log(i);

That will output 0 and 2.

To get the actual index:

var tested = ['foot','bark', 'foo','cat'];
var match = 'foo';
var index = -1;
for(var i = 0; i < tested.length; i++) {
    if(tested[i].indexOf(match) > -1) {
       index = i;
       break;
    }
} 

console.log(index); // 0, as "foot" includes "foo".

answered Mar 14, 2016 at 16:03

cwallenpoole

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2 Comments

Isla Over a year ago

I'm looking for 'foobar' and 'foo', but indexOf returns ONLY 'foo'

Isla Over a year ago

nice, thank you, but my own solution I already have, question was about existing in JavaScript solution, like mentioned findIndex().

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