Using underscore.js to compare two Objects

Question

I'm trying to compare two objects with underscore.

Object 1 (Filter)

{
  "tuxedoorsuit":"tuxedoorsuit-tuxedo",
  "occasions":"occasions-wedding"
}

Object 2 (Properties)

{
  "tuxedoorsuit":"tuxedoorsuit-tuxedo",
  "occasions":"occasions-wedding",
  "occasions":"occasions-prom",
  "product_fit":"product_fit-slim",
  "colorfamily":"colorfamily-black"
}

I want to return true when all items of Object 1 are found within Object 2. What would be the best underscore method to use for this?

What about underscorejs.org/#isEqual and underscorejs.org/#isMatch ? — Arnaldo Ignacio Gaspar Véjar
– Arnaldo Ignacio Gaspar Véjar, Commented Feb 20, 2015 at 15:26
@ArnaldoIgnacioGasparVéjar: You should make that an answer. It's much better than the currently accepted. — Bergi
– Bergi, Commented Feb 20, 2015 at 16:30
@Bergi : I agree isMatch would be far better. But actually it's interesting to note that it won't work in this case, because "Object 2" is malformed. It has two times the same property occasions. isMatch casts "Object 2" to a standard Object and this will only keep the last value of this property : occasions-prom. It will then return false. — slaur4
– slaur4, Commented Feb 20, 2015 at 16:55
@ArnaldoIgnacioGasparVéjar Ah, nice :) I included isMatch in my answer. Thanks :) — thefourtheye
– thefourtheye, Commented Feb 21, 2015 at 4:40
@slaur4: In fact, that the object syntax is malformed causes the parser to drop the "first" value (or, in strict mode, to throw a syntax error). isMatch is not to blame here, any other method would work the same - except when it would take object 2 as JSON and used a tolerant parser internally. — Bergi
– Bergi, Commented Feb 21, 2015 at 12:07

tagurit · Accepted Answer · 2022-12-30 01:30:57Z

36

Edit: As per Arnaldo's comment, you can use isMatch function, like this

console.log(_.isMatch(object2, object1));

The description says,

_.isMatch(object, properties)

Tells you if the keys and values in properties are contained in object.

If you want to iterate yourself, just use _.keys and _.every, like this

_.every(_.keys(object1), function(currentKey) {
    return _.has(object2, currentKey) &&
        _.isEqual(object1[currentKey], object2[currentKey]);
});

Or the chained version,

var result = _.chain(object1)
    .keys()
    .every(function(currentKey) {
        return _.has(object2, currentKey) &&
            _.isEqual(object1[currentKey], object2[currentKey]);
    })
    .value();

If the result is true, it means that all the keys in object1 are in object2 and their values are also equal.

This basically iterates through all the keys of object1 and checks if the value corresponding to the key in object1 is equal to the value in object2.

edited Dec 30, 2022 at 1:30

tagurit

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answered Feb 20, 2015 at 15:20

thefourtheye

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Casey Over a year ago

How would I use this inside _.filter?

thefourtheye Over a year ago

@Casey Please edit the question and include all the information

Casey Over a year ago

This worked great! I was able to modify it a bit to work inside _.filter(). Thanks!

Casey Over a year ago

Actually, it looks like if the first item of object1 is found, then it won't check the second item.

thefourtheye Over a year ago

@Casey JavaScript objects are HashMap implementations. So, if there are two items which are mapped to the same Hash value, then either of them will be overwritten by the other one.

Matt · Accepted Answer · 2016-01-28 10:21:26Z

12

To Compare two objects using underscore.js

 **isEqual :** _.isEqual(object, other)

Performs an optimized deep comparison between the two objects, to determine if they should be considered equal.

Ex :

var stooge = {name: 'moe', luckyNumbers: [13, 27, 34]};
    var clone  = {name: 'moe', luckyNumbers: [13, 27, 34]};
     _.isEqual(stooge, clone)  
      Returns True

edited Jan 28, 2016 at 10:21

Matt

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answered Jan 28, 2016 at 9:48

pradeep gowda

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Emile Bergeron Over a year ago

While isEqual is quite useful, it won't work if the other object has an additional property, like in OP's case.

zero_cool Over a year ago

It will also not work if the order of keys is not identical :/

Akash Agarwal Over a year ago

@zero_cool order of keys shouldn't matter. JSON only orders arrays, not hashes.

Dmitri Algazin · Accepted Answer · 2017-03-16 17:02:07Z

1

Based on previous function created simple consoling out function:

var compareMe = function (obj1, obj2, parentKey) {
  parentKey = parentKey || '';
  _.each(_.keys(obj1), function (key) {
    if(_.isObject(obj1[key]) ) {
        compareMe(obj1[key], obj2[key], parentKey + key + '.')
    } else {
        if (!_.has(obj2, key) || !_.isEqual(obj1[key], obj2[key])) {
            console.log(parentKey + key, obj1[key], obj2[key]);
        }
    }
  })
};

And call like: compareMe(obj1, obj1)

answered Mar 16, 2017 at 17:02

Dmitri Algazin

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