Merge pull request #1660 from jchue/patch-2
Make minor grammar corrections/updates to async/promise-basics
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commit
c92effe162
1 changed files with 8 additions and 8 deletions
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@ -31,9 +31,9 @@ When the executor obtains the result, be it soon or late - doesn't matter, it sh
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- `resolve(value)` — if the job finished successfully, with result `value`.
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- `reject(error)` — if an error occurred, `error` is the error object.
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So to summarize: the executor runs automatically, it should do a job, and then call either `resolve` or `reject`.
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So to summarize: the executor runs automatically and performs a job. Then it should call `resolve` if it was succssful or `reject` if there was an error.
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The `promise` object returned by `new Promise` constructor has internal properties:
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The `promise` object returned by the `new Promise` constructor has internal properties:
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- `state` — initially `"pending"`, then changes to either `"fulfilled"` when `resolve` is called or `"rejected"` when `reject` is called.
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- `result` — initially `undefined`, then changes to `value` when `resolve(value)` called or `error` when `reject(error)` is called.
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@ -58,7 +58,7 @@ let promise = new Promise(function(resolve, reject) {
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We can see two things by running the code above:
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1. The executor is called automatically and immediately (by `new Promise`).
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2. The executor receives two arguments: `resolve` and `reject` — these functions are pre-defined by the JavaScript engine. So we don't need to create them. We should only call one of them when ready.
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2. The executor receives two arguments: `resolve` and `reject`. These functions are pre-defined by the JavaScript engine, so we don't need to create them. We should only call one of them when ready.
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After one second of "processing" the executor calls `resolve("done")` to produce the result. This changes the state of the `promise` object:
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@ -79,7 +79,7 @@ The call to `reject(...)` moves the promise object to `"rejected"` state:
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To summarize, the executor should do a job (something that takes time usually) and then call `resolve` or `reject` to change the state of the corresponding promise object.
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To summarize, the executor should perform a job (usually something that takes time) and then call `resolve` or `reject` to change the state of the corresponding promise object.
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A promise that is either resolved or rejected is called "settled", as opposed to an initially "pending" promise.
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@ -166,7 +166,7 @@ promise.then(
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The first function was executed.
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And in the case of a rejection -- the second one:
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And in the case of a rejection, the second one:
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```js run
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let promise = new Promise(function(resolve, reject) {
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@ -205,7 +205,7 @@ let promise = new Promise((resolve, reject) => {
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});
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*!*
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// .catch(f) is the same as .then(null, f)
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// .catch(f) is the same as promise.then(null, f)
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promise.catch(alert); // shows "Error: Whoops!" after 1 second
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*/!*
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```
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