Created
May 21, 2015 04:12
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Promises pop quiz: can you articulate the difference(s) between these two snippets?
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| function foo() { | |
| return new Promise(function(resolve){ | |
| mayThrow(); | |
| resolve("foo"); | |
| }); | |
| } |
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| function foo() { | |
| return Promise.resolve().then(function(){ | |
| mayThrow(); | |
| return "foo"; | |
| }); | |
| } |
How about: mayThrow() runs synchronously in the first but not second. Maybe that's a nit-pick, but I can see how it could trip someone up in certain circumstances.
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gistfile2.js --> The promise is not resolved and always goes into pending state. And also by definition , The Promise.resolve(value) method returns a Promise object that is resolved with the given value. Here , We are not providing the any value to the promise i.e., success, reject.
gistfile1.js --> Its actually goes ahead and creates an instance of the Promise with new. And hence, code gets executed till the end within the anonymous function.