shareExecution

gistfile1.txt

(async function(){
    const shareExecution = (callback) => {
        let loading;
    
        return async function () {
            if (!loading) {
                loading = callback();
                loading.finally(() => loading = null)
            }
    
            return loading;
        }
    };

    async function delay(ms) {
        return new Promise(resolve => setTimeout(resolve, ms));
    }
    
    let callCount = 0;
    const shared = shareExecution(() => delay(3000).then(() => callCount++));
    shared().then((c) => console.log(c, 1));
    shared().then((c) => console.log(c, 2));
    shared().then((c) => console.log(c, 3));

    await delay(1000);
        
    shared().then((c) => console.log(c, 4));

    await delay(4000);
    
    shared().then((c) => console.log(c, 'new'));

    
})()