I'm using Chai.js and I'm trying to check if an object contains a partial key. Let me explain:

I have this object to test:

var obj = {
    "one/two/three": "value"
}

And I want to check using Chai.js if the object obj contains a partial key "one" which is include in the key "one/two/three".

Here I check that a key is included:

({ foo: 1, bar: 2 }).should.have.keys('bar');
({ foo: 1, bar: 2, baz: 3 }).should.include.keys('foo');
({ foo: 1, bar: 2, baz: 3 }).should.contain.keys('baz');

And here I check if a string contains a substring:

'foobar'.should.match(/^foo/)

Then, I would like to merge both to have something like this:

({ foo: 1, bar: 2, baz: 3 }).should.contain.keys.which.match('fo');

Do you know a way to handle this?

Thanks for your help!

I'm using Chai.js and I'm trying to check if an object contains a partial key. Let me explain:

I have this object to test:

var obj = {
    "one/two/three": "value"
}

And I want to check using Chai.js if the object obj contains a partial key "one" which is include in the key "one/two/three".

Here I check that a key is included:

({ foo: 1, bar: 2 }).should.have.keys('bar');
({ foo: 1, bar: 2, baz: 3 }).should.include.keys('foo');
({ foo: 1, bar: 2, baz: 3 }).should.contain.keys('baz');

And here I check if a string contains a substring:

'foobar'.should.match(/^foo/)

Then, I would like to merge both to have something like this:

({ foo: 1, bar: 2, baz: 3 }).should.contain.keys.which.match('fo');

Do you know a way to handle this?

Thanks for your help!

• javascript
• regex
• key
• chai
• contain

• I'd be very surprised if Chai has a built-in assertion for this, but its documentation does talk about how to add your own. Adding your own for the above would be fairly trivial. – T.J. Crowder Commented Sep 30, 2016 at 8:31
• I've just found docs about creating my own, looks like interesting, thanks! – Barudar Commented Sep 30, 2016 at 8:38

1 Answer 1

The simplest way I can think of to do this is iterate over the Object's keys and check if any of them match the regular expression.

Object.keys({ foo: 1, bar: 2, baz: 3 }).some(function(key) {
    if (key.match(/^foo/) != null) {
        return true;
    }
    return false;
});

You can then wrap this in some chai code to achieve the desired result like so:

expect(Object.keys({ foo: 1, bar: 2, baz: 3 }).some(function(key) {
    if (key.match(/^foo/) != null) {
        return true;
    }
    return false;
})).to.equal(true);

In case you're unfamiliar with Array.some, it will immediately return true as soon as it reaches any key that causes its callback to return a truthy value.