This challenge originates from my “Embrace Wacky JavaScript” presentation. I thought I could publish it in my blog and talk through some of this crazy logic.

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const globals = {
    zero: 0,
    one: 1
}

function main() {
    let zero = 0;
    let one = "" + ++zero + !!"hello".length + [" ", "world"];

    let clearUp = one.replace(",", "");

    if (this.zero && one) {
        console.log(clearUp);
    } else {
        console.log(clearUp);
    }
};

const saying = main.bind(globals)
saying();

There is a main function and a globals function. The main’s function parent object will be bound to globals and assigned to saying. I could as well have used an apply or call method and pass in globals as the first parameter.

In the function I have three variables: there are zero, one, and clearUp. zero and clearUp variables are pretty straightforward. I’ll need to talk about the one variable.

There are a couple sections. "" + ++zero, !!"hello".length, and [" ", "world"].

In "" + ++zero, the first thing that happens is zero variable is incremented by one. Then it is concatenated into an empy string, so the incremented value will be coerced as a string. This expression results "1".

In the next section (!!"hello".length), .length gets evaluated first, so the expression turns into !!5. With the double bang operators, the number value is coerced into false then true.

So the expression for the one variable is this, "1" + true + [" ", "world"]. The plus signs here are concatenators, so every different datatype will be coerced into a string and attached to each other. The value assigned to the one variable is "1true ,world". clearUp variable removes the comma.

The remaining if condition sees this.zero from its parent object. That value is 0. That value is falsey and fails the condition. Either way the same thing gets logged. I didn’t put much difference here.

Why

As I mentioned in my previous post, JS is just plain weird. So this was an exercise to try and see how weird and valid I can get JS. By all means, this code is very bad and impractical. If ever used I suspect it will confuse some developers greatly.