Need help understanding lodash's _.includes method

Question

I would like to use lodash's _.includes method in my code, but any time I have an array of objects I can't get it to work, and instead end up relying on the _.find method.

From my tests I can only get _.includes to work with simply arrays. But maybe that's the way it's supposed to work?

I am very new to Lodash and programming in general, so I thought I would ask in case I am missing something about how I can use this method.

I created a jsbin with the following code: http://jsbin.com/regojupiro/2/

var myArray = [];

function createArray(attName, attId, otherId) {
    var theObject = {};

    theObject.attributeName = attName;
    theObject.attributeId = attId;
    theObject.otherId = [otherId];

      return theObject;
}

myArray.push(createArray('first', 1001, 301));
myArray.push(createArray('second', 1002, 302));
myArray.push(createArray('third', 1003, 303));
myArray.push(createArray('fourth', 1004, 304));

var isPresent1 = _.includes(myArray, {'attribtueId' : 1001});
var isPresent2 = _.includes(myArray, 1001);
var found = _.find(myArray, {'attributeId' : 1001});

console.log(isPresent1);
console.log(isPresent2);
console.log(found);
console.log(myArray);

Both "isPresent" variables return false, but the _.find method returns the correct object.

I would love some help in better understanding how I could use the _.includes method when I just need to do a simple true/false check to see if a value is present in my array of objects.

Or, if this is the wrong tool for the job, is the _.find method the right tool for this job, or some other lodash method that I'm not familiar with yet?

Thank you for your help!

Answer 1

I think some() does exactly what you're looking for.

Answer 2

The _.includes() method compares with the SameValueZero comparator, which is a special comparison mostly like ===. Even if you have an object in your array that looks like {'attribtueId' : 1001} that _.includes() call will never find it because two distinct objects will never compare as === to each other.

When you pass an object to _.find(), by contrast, the library assumes that you want it to carry out an _.matches() comparison, which will compare properties of the "target" object. Thus, in your case, _.find() is probably the right choice. The _.includes method really fills a distinct niche.