35 lines
1.5 KiB
Markdown
35 lines
1.5 KiB
Markdown
### onUserInputChange
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Will run the callback whenever the user changes their input type (either `mouse` or `touch`). This is useful
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if you want to disable certain code depending on if the user is using touch as input or a mouse (including trackpads).
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Use two event listeners. Assume `mouse` input initially and bind a `touchstart` event listener to the document.
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On `touchstart`, the callback is run and supplied with the current input type as an argument.
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Then, add a `mousemove` event listener to listen for two consecutive `mousemove` events firing within 20ms
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using `performance.now()` (browsers recently fire them every animation frame). Run the callback and supply the new type
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`mouse` as the argument. This process needs to happen dynamically because of hybrid devices (such as a touchscreen laptop),
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where the user can switch between either input type at will.
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```js
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const onUserInputChange = callback => {
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let type = 'mouse', lastTime = 0;
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const mousemoveHandler = () => {
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const now = performance.now();
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if (now - lastTime < 20) {
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type = 'mouse', callback(type), document.removeEventListener('mousemove', mousemoveHandler);
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}
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lastTime = now;
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};
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document.addEventListener('touchstart', () => {
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if (type === 'touch') return;
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type = 'touch', callback(type), document.addEventListener('mousemove', mousemoveHandler);
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});
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};
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```
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```js
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onUserInputChange(type => {
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console.log('The user is now using', type, 'as an input method.');
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});
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```
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