Category Archives: Programming

How to analyze the performance of your go application in production

You should definitely use chi’s middleware for running pprof and stuff in your admin panel. That’s the repo — https://github.com/go-chi/chi That’s the profiler — https://github.com/go-chi/chi/blob/master/middleware/profiler.go CPU profiling After that you can run something like this in shell:

go tool pprof -png ~/Downloads/profile

1	go tool pprof -png ~/Downloads/profile

Or just open it in the browser:

go tool pprof -http=:1234 ~/Downloads/profile

1	go tool pprof -http=:1234 ~/Downloads/profile

If it opens something different then your browser (sublime …

GOPROXY=https://<some_url> go mod download

1	GOPROXY=https://<some_url> go mod download

Nice list of image resizer libs in go

With speedtests and other nice things. https://github.com/fawick/speedtest-resize I tried these two: https://github.com/disintegration/imaging https://github.com/bamiaux/rez They are quite the same talking about file sizes and imaging is muuch easier to use.

Simple way to detect browser’s FPS via JS

It’s dumb and dead simple but works. You can even track browser’s metrics with that.

(() => {
    const times = [];
    let fps;

    function refreshLoop() {
        window.requestAnimationFrame(() => {
            const now = performance.now();
        while (times.length > 0 && times[0] <= now - 1000) {
            times.shift();
        }
        times.push(now);
        fps = times.length;
        refreshLoop();
    });
    }
    refreshLoop();
    
    // output to console once per second
    setInterval(() => {console.log(fps);}, 1000)
})();

(() => {

const times = [];

let fps;

function refreshLoop() {

window.requestAnimationFrame(() => {

const now = performance.now();

while (times.length > 0 && times[0] <= now - 1000) {

times.shift();

}

times.push(now);

fps = times.length;

refreshLoop();

});

}

refreshLoop();

// output to console once per second

setInterval(() => {console.log(fps);}, 1000)

})();

Mocking for testing go code

If you’re testing go code and have a huge API you have to mock, you have two options: make your dummy struct with embedded interface and implement only methods you need, or use your own interface that has only methods you need (and change your code to use that). For instance, I had amazon’s s3 …

BDD Framework For Golang

There is a good one: https://github.com/onsi/ginkgo It prefers to use http://onsi.github.io/gomega/ as a matcher.

Golang, PostgreSQL and array_agg

If you have SQL like this:

Simple online editor for javascript

Just paste it into navigation bar:

data:text/html, <html><script>window.onbeforeunload = window.onunload = function(){return 'Confirm page reload';};</script><body><button onclick="console.log(eval(document.querySelector('textarea').value.replace('<div>', '\n').replace('</div>', '\n')))">run</button><br><textarea style="width:600px;height:400px"></textarea></body><script>document.querySelector('textarea').focus();</script>

data:text/html, <html><script>window.onbeforeunload = window.onunload = function(){return 'Confirm page reload';};</script><body><button onclick="console.log(eval(document.querySelector('textarea').value.replace('<div>', '\n').replace('</div>', '\n')))">run</button><br><textarea style="width:600px;height:400px"></textarea></body><script>document.querySelector('textarea').focus();</script>

It just outputs the result into console when you click run button. It’s simple and works. Because sometimes you just don’t need monsters like jsfiddle or jsbin.

Storybook for creating components library

It works with all popular frameworks like React, Angular, Vue, and others. https://github.com/storybooks/storybook

React, redux and redux-thunk with typescript

I tried it and it looks strange, verbose and painful. But if you want to try it, please take a look at: https://github.com/piotrwitek/react-redux-typescript-guide https://levelup.gitconnected.com/react-and-redux-with-typescript-da0c37537a79 (together with https://github.com/JonJam/react-redux-ts/tree/68e8cca4a6e6214b4acb030cf3fdb3321b636085/src)