I'm struggling to extract the string "foo" from my Promise. I'm starting to think that my Promise declaration is incorrect.
const bar = new Promise((res, rej) => res("foo"));
then((result) => {
return result;
});
I'm struggling to extract the string "foo" from my Promise. I'm starting to think that my Promise declaration is incorrect.
const bar = new Promise((res, rej) => res("foo"));
then((result) => {
return result;
});
Here is the recommended approach:
const variable = new Promise((resolve, reject) => resolve("value"));
variable.then((result) => {
console.log(result);
// perform any desired actions with result
}).catch(error=>console.log(error))
The then function gets executed upon successful resolution of the promise.
The catch method triggers when the promise is rejected.
const example = new Promise((resolve) => resolve("hello"))
.then((output) => {
console.log(output)
});👉 Remember to include a period (.) before the word then -> .then
then is a method of the Promise object, so you must use .then to invoke the method. then cannot be used independently as a global function.
When you write:
new Promise((resolve) => resolve("hello")).then((output) => ...
the then will only execute upon successful resolution of the Promise.
The Promise internally tracks all then methods and triggers them when you call resolve("hello") (in this case), hence the need for .then - to register those callbacks to be executed upon resolution
When you assign the Promise to the variable bar, make sure to use then to retrieve the value like this:
const bar = new Promise((res, rej) => res("foo")).then((result) => {
console.log(result)
});
It's also important to include a catch statement for error handling.
If you're looking to learn more about Promises, check out this free course on Udacity from Google to improve your understanding.
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