Handwritten promise all

/** * * @param {iterator} proms */
Promise.all = function (proms) {
    

    return new Promise((resolve, reject) => {
    
        try {
    
            let count = 0; //  How many proms
            let resolvedCount = 0; //  How many promise already resolve

            let results = [] // resolve The result is an array 

            for (const pro of proms) {
     // proms Not necessarily arrays , Should be an iterator 
                let curIndex = count; //  Record this promise resolve Then return the index of the array 
                count++;

                Promise.resolve(pro).then(data => {
     //  It may not be one promise, So we need to pack it 

                    results[curIndex] = data;
                    resolvedCount++;
                    if (count === resolvedCount) {
    
                        //  all promise already resolved, Trigger return Promise Of resolve
                        resolve(results);
                    }
                }, reject) //  If there is an error, call reject
            }
            if (count === 0) {
    
                //  It is possible that an empty array is passed in 
                resolve(results);
            }
        } catch (error) {
    
            reject(error)  //  If an error occurs in the process , Direct trigger return promise Of reject
        }
    })
}

Promise.all([1,2,Promise.resolve(3),Promise.reject(0)]).then(data=>{
    
    console.log(data);
}).catch(err=>{
    
    console.log(err);
})

Promise.all(null).then(data=>{
    
    console.log(data);
}).catch(err=>{
    
    console.log(err);
})