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30-seconds-of-code/snippets/hamburger-button.md
2019-11-25 07:15:06 +11:00

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---
title: Hamburger Button
tags: interactivity,beginner
---
This is a way to build simple hamburger button for menu bar.
```html
<div class="hamburger-menu">
<div class="top"></div>
<div class="middle"></div>
<div class="bottom"></div>
</div>
```
```css
.hamburger-menu {
display: flex;
flex-direction: column;
flex-wrap: wrap;
justify-content: space-between;
height: 2.5rem;
width: 2.5rem;
cursor: pointer;
.bar {
height: 5px;
background: black;
border-radius: 5px;
margin: 3px 0px;
transform-origin: left;
transition: all 0.5s;
}
&:hover {
.top {
transform: rotate(45deg);
}
.middle {
opacity: 0;
}
.bottom {
transform: rotate(-45deg);
}
}
}
```
#### Explanation
- Use a `hamburger-menu` container div to which contanins the top, bottom and middle bars.
- The container is set to be a flex container (`display: flex`) with `flex-direction` to be `column` and `flex-wrap` to be `wrap`.
Alternatively, you can set both properties by a shorthand `flex-flow: column wrap`
- We add distance between the bars using `justify-content: space-between`
- The animation has 3 parts, top and bottom bars transforming to 45 degree angles (`rotate(45deg)`) and the middle bar fading away by setting the `opacity: 0`
- The `transform-origin` is set to `left` so the rotation point of origin is left
- We set `transition all 0.5s` so that both `transform` and `opacity` are properties are animated for half a second
#### Browser support
- Flexbox - https://caniuse.com/#feat=flexbox
- CSS Transitions - https://caniuse.com/#feat=css-transitions