28 lines
828 B
Markdown
28 lines
828 B
Markdown
---
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title: defer
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tags: function,intermediate
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firstSeen: 2018-01-01T23:40:31+02:00
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lastUpdated: 2020-10-22T20:23:47+03:00
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---
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Defers invoking a function until the current call stack has cleared.
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- Use `setTimeout()` with a timeout of `1` ms to add a new event to the event queue and allow the rendering engine to complete its work.
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- Use the spread (`...`) operator to supply the function with an arbitrary number of arguments.
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```js
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const defer = (fn, ...args) => setTimeout(fn, 1, ...args);
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```
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```js
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// Example A:
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defer(console.log, 'a'), console.log('b'); // logs 'b' then 'a'
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// Example B:
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document.querySelector('#someElement').innerHTML = 'Hello';
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longRunningFunction();
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// Browser will not update the HTML until this has finished
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defer(longRunningFunction);
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// Browser will update the HTML then run the function
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```
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