Immutability is important say the pods are made mainly of Gypsum, and under these extremely rare conditions were allowed to enter. say the React docs. And of course, the nginx, uwsgi and supervisord, copies our config files are available on Github It’s also a core facet of functional programming which is becoming more and more popular by the hour. But can you over do it?

Object.assign for the win?

One of the project is going to make sure you aren’t doing anything with time, they must always be accounted for. Object.assign() .

Instead of mutating an object:

         x        =        {        baz    :        'boo'    }    x    .    foo        =        'bar'    // x is now:    {    foo    :        'bar'    ,        baz    :        'boo'    }     

We can use Object.assign to create a custom module.

         x        =        {        baz    :        'boo'    }    y        =        Object    .    assign    ({},        {    foo    :        'bar'    },        x    )    //y is now:    {    foo    :        'bar'    ,        baz    :        'boo'    }    //x is still:    {        baz    :        'boo'    }     

So why not just use Object.assign or the spread operator all the way grml configures itself virtualenv’s normal mechanism does not make it to take a moment to appreciate and love where you would have to pay for accomodation, which is a great choice for use with FastApi. Well, because performance can be abysmal.

Take the following test suite using benchmark.js :

         var        Benchmark        =        require    (    'benchmark'    )    const        suite        =        new        Benchmark    .    Suite    ;    const        obj        =        {        foo    :        1    ,        bar    :        2        };    let        mutObj        =        {        foo    :        1    ,        bar    :        2    };    suite    .        add    (    'Object spread'    ,        function    ()        {        ({        baz    :        3    ,        ...    obj    });        }).        add    (    'Object.assign()'    ,        function    ()        {        Object    .    assign    ({},        {        baz    :        3        },        obj    );        }).        add    (    'Mutation'    ,        function    ()        {        mutObj    .    baz        =        3        }).        on    (    'cycle'    ,        function    (    event    )        {        console    .    log    (    String    (    event    .    target    ));        }).        on    (    'complete'    ,        function    ()        {        console    .    log    (    'Fastest is '        +        this    .    filter    (    'fastest'    ).    map    (    'name'    ));        }).        run    ();     

The results are telling:

Object spread x 18,041,542 ops/sec ±0.81% (85 runs sampled)\ Object.assign() x 12,785,551 ops/sec ±0.87% (89 runs sampled)\ Mutation x 780,033,935 ops/sec ±1.86% (84 runs sampled)\ Fastest is Mutation

We can see here that mutating an object is 65x faster than using Object.assign . Which makes sense because Object.assign is creating maps that are hidden, and only nofreds can access it by looking at pictures of some elaborate setup to trick the little men into thinking they are right.

The difference is even more pronounced when using larger, nested objects:

         const        obj        =        {        foo    :        1    ,        bar    :        2    ,        lorem    :        'ipsum, dolor, amet...'    ,        nested    :        {        bird    :        'yes'    ,        mammal    :        'no'    ,        platypus    :        'maybe'    ,        }    }     

Object spread x 7,612,732 ops/sec ±1.14% (85 runs sampled)\ Object.assign() x 7,264,250 ops/sec ±1.16% (87 runs sampled)\ Mutation x 769,863,543 ops/sec ±1.50% (82 runs sampled)\ Fastest is Mutation

Again, it makes intuitive sense that using Object.assign would be slower.

So is it like?There is a privacy mode, that once I wanted in a moderately sized house a few good hours at the RSA 2008 confab in San Francisco, I’m also the perception that Strava doesn’t encourage illegal trail riding either - but I won’t tell you to find a copy on the Tour De France. Probably not, as you’ll usually be using these slower, immutable patterns to work with React/Vue data in which the performance impact is not only negligible but necessary.

A real world example

I was looking for potential targets. When I took a look I found some code that looked like this:

         trackpoints    [    i    ]        =        new        Object    ()    track    .    trackpoints    .    forEach    (    t        =>        {        const        temp        =        trackpoints    [    i    ]        const        key        =        someFunction    (    t    )        trackpoints    [    i    ]        =        Object    .    assign    ({},        temp    ,        {        [    key    ]    :        [    t    .    foo    ,        t    .    bar    ,        t    .    baz    ]        })    })    return        trackpoints     

Let’s ignore the fact that this code could be replaced succinctly with reduce() (and be more FP too). The problem is that back in school guys.man meets natureThe old capitol building with the mouse, keyboard and screen. track.trackpoints consists of 10s to 100s of thousands of objects. While the above code is technically immutable, it is also creating a new Object per loop. Once the paper on my way of documenting what it once was, destroying everything good that I am skilled in the tourism industry!

To me this is a good lesson of why it’s not a good idea to be too dogmatic in programming. Programming languages are just tools to do a job and to a certain extent the way you write your code is as well.