Difference between promise-chain and promise.all() in Javascript
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![Promise.all()
Executes all promises concurrently and returns a
single promise when all of the promises are
fulfilled for their results.
const promise1 = Promise.resolve("I");
const promise2 = Promise.resolve("❤️");
const promise3 = Promise.resolve("JS");
const promise4 = Promise.resolve("NUGGETS");
Promise.all(
[promise1, promise2, promise3, promise4]
).then((values) => {
console.log(values);
});
// Output: ["I", "❤️", "JS", "NUGGETS"]
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Difference between promise-chain and promise.all() in Javascript
- 1. Promise-chain (vs) Promise.all() ● Executes one by one (synchronous). ● Result of one execution can be passed to the next step. ● Execution time to fulfill all the promise is comparatively high. ● Chaining after an error is possible. ● Executes in parallel (asynchronous). ● Result of one promise cannot be passed to an another promise. ● Parallel execution guarantees in reduced time. ● It rejects with the reason of the first promise that rejects. Brought to you by JS Mastery & Ideas2IT
- 2. Promise-chain Executes two or more asynchronous operations back to back, where each subsequent operation starts when the previous operation succeeds, with the result from the previous step. let chain = new Promise((resolve, reject) => { resolve("I "); }).then((result_1) => { return result_1 + "❤️"; }).then((result_2) => { return result_2 + " JS "; }).then((result_3) => { return result_3 + "NUGGETS"; }); // Output: "I ❤️ JS NUGGETS" Brought to you by JS Mastery & Ideas2IT
- 3. Promise.all() Executes all promises concurrently and returns a single promise when all of the promises are fulfilled for their results. const promise1 = Promise.resolve("I"); const promise2 = Promise.resolve("❤️"); const promise3 = Promise.resolve("JS"); const promise4 = Promise.resolve("NUGGETS"); Promise.all( [promise1, promise2, promise3, promise4] ).then((values) => { console.log(values); }); // Output: ["I", "❤️", "JS", "NUGGETS"] Brought to you by JS Mastery & Ideas2IT