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50 lines
2.1 KiB
50 lines
2.1 KiB
6 years ago
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# Dynamic CSS Variables
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**Tier:** 1-Beginner
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CSS variables are a powerful tool that lets the developer associate a symbolic
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name with a value, and then use that name in the stylesheet whereever that
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value is required. The advantage is that when a change to that value is
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required it only needs to change in the CSS variable definition rather than in
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the many spots it may be used.
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What can make this even more powerful is to dynamically change the value of a
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CSS variable at runtime.
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The goal of this app is to dynamically change the background color of text boxes
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based to let you gain experience using both CSS variables and dynamically
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changing them from within the app.
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## User Stories
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- [ ] User can see three two boxes to be used to enter a User ID and Password
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along with 'Cancel' and 'Login' buttons underneath them. The default background
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color of the text boxes is white.
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- [ ] User can enter a user id and password into the text boxes.
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- [ ] User can click the 'Login' button to validate the user id and password.
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- [ ] User can see a warning message if one or both of the text boxes contains
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spaces and the background color of the empty text box will change to light
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yellow.
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- [ ] User can see a warning message if the user id doesn't match 'testuser'
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and the background color of the text box will change to light red.
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- [ ] User can see a warning message if the password doesn't match 'mypassword'
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and the background color of the text box will change to light red.
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- [ ] User can click the 'Cancel' button to clear the text boxes and reset
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their background colors to white.
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## Bonus features
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- [ ] User can see the color of the text box border change when an error is
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detected
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- [ ] User can see the size and font of the contents of the text box change
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when an error is detected.
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## Useful links and resources
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- [Custom properties (--*): CSS variables (MDN)](https://developer.mozilla.org/en-US/docs/Web/CSS/--*)
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- [CSSStyleDeclaration (MDN)](https://developer.mozilla.org/en-US/docs/Web/API/CSSStyleDeclaration)
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## Example projects
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[Dynamic CSS Variables](https://codepen.io/gordawn/pen/oOWBXX)
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