slots

A basic execution throttling library with named slots.

import {Slots} from "@mukunda/slots";

push mode cancels previous pending timer. For example, if a user is actively typing in a search query and each key press starts a push slot, then it will only call the search API when they are done typing.

// Call callback after 500ms
Slots.start("myslot", "push", 500, callback);

sleep(300);

// Cancels previous call and call it in another 500ms.
Slots.start("myslot", "push", 500, callback);

cooldown mode fires instantly or after a certain cooldown period passes. For example, when a user clicks on a button once, they get instant results. If they click it several times, requests to the server are delayed and only sent after each cooldown period.

function myClickHandler() {
    // If you click this button 5 times within 3 seconds,
    //  the callback will only trigger twice. Once on the
    //  first click, and again after the cooldown expires.

    // In other words, if the cooldown is "active", then
    //  the next execution is scheduled for when the
    //  cooldown expires.

    Slots.start("myslot", "cooldown", 3000, () => {
        // Perform expensive API call.
    }));
}

ignore mode throws away new executions if one is currently scheduled.

// Only triggers once after the first expires.
Slots.start("myslot", "ignore", 500, callback);
Slots.start("myslot", "ignore", 500, callback);
Slots.start("myslot", "ignore", 500, callback);

Callbacks can be async functions. In that case, further executions are delayed further if a previous callback is still executing.

• ignore will wait until the delay plus the callback completes before further scheduling is allowed.
• push triggers will delay longer if an execution is in progress. If another push happens during this additional delay, the previous push will be canceled.
• cooldown triggers work like ignore when on cooldown.