JavaScript: Difference between revisions

JavaScript (view source)

595 bytes added , 18 March 2020

5,321

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    }
 }
+</syntaxhighlight>
+==Promises==
+See [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise Promises]<br>
+In general, a function returns a promise if it needs to perform asyncronous tasks.<br>
+<syntaxhighlight lang="javascript">
+function myFunc() {
+  // Do syncronous things here
+  return new Promise((resolve, reject) => {
+    // Do asyncronous things here
+    // Return data
+    resolve(myData);
+    // Or if we have an error
+    reject(myError);
+  });
+}
+myFunc()
+  .then(data => {
+     console.log(data);
+  }).catch(err => {
+     console.error(err);
+  });
 </syntaxhighlight>