Go-style CSP in JavaScript

csp.js

const CLOSED = Symbol('chan-closed');
const StackGC = async () => null;

class Chan {
    constructor(size) {
        this.q = [];
        this.size = size || 1;
        this.isClosed = false;
    }

    async put(x) {
        if (this.isClosed)
            return false;
        else if (this.q.length == this.size) {
            await StackGC();
            return await this.put(x);
        } else if (x === CLOSED) {
            this.isClosed = true;
            return true;
        }else {
            this.q.push(x);
            return true;
        }
    }

    async take() {
        if (this.isClosed && this.q.length === 0)
            return CLOSED;
        else if (this.q.length === 0) {
            await StackGC();
            return await this.take();
        } else
            return this.q.shift();
    }

    async close() {
        this.put(CLOSED);
    }
}

async function go(f) {
    return await f();
}


// Tests
// =====
function test1() {
    let ch = new Chan();
    go(async () => {
        console.log('got:', await ch.take());
    });
    ch.put('hi!');
}

function test2() {
    // takes and prints values from channel
    // till it is closed
    async function printAll(ch) {
        while(true) {
            let x = await ch.take();

            if (x === CLOSED)
                break;
            
            console.log(x);
        }
    }

    let ch = new Chan();
    ch.put(0);
    ch.put(1);
    ch.put(2);
    ch.close();
    ch.put(3);

    printAll(ch);
}