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title: Notes about BEM (Block Element Modifier) |
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date: "2021-02-02" |
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--- |
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In the coming weeks, months and years, I will be working on frontend-development as part of my dayjob. These are some personal notes I took during my research about the BEM methodology. If you want to read the official introduction, you should visit [their website](http://getbem.com/). |
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# Overview - What is BEM? |
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BEM — Block Element Modifier is a methodology that helps you to create reusable components and code sharing in front-end development. It aims to group css-classes in a meaningful way, making it easier to understand |
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1. where this class is used |
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2. what it describes and |
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3. what state the element is in. |
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The BEM-notation is divided into three main parts: Blocks, Elements and Modifiers. |
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## Blocks |
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A standalone entity that is meaningful on its own. Some examples might be **headers, containers, menus, inputs, checkboxes**, etc. |
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## Elements |
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A part of a block that has no standalone meaning and is semantically tied to its block. This could be a **menu item or an input placeholder**. |
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## Modifiers |
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A flag on a block or an element. Used to change appearance or behavior. This might be **disabled, checked, fixed, big**, etc. |
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Putting it together |
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A block itself is referenced though its name. |
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```css |
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.button { |
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} |
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``` |
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To reference elements inside of the block, you add it to the block element with two underscores (`__`): |
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```css |
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.button { |
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} |
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.button__text { |
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} |
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``` |
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If you want to add a modifier to a block or an element, you separate it with two dashes (`--`): |
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```css |
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.button { |
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} |
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.button--disabled { |
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} |
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.button__text--inverted { |
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} |
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``` |
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# Benefits of BEM |
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**Modularity**: Block styles never depend on one another. They can easily be moved to other parts of the app. |
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**Reusability**: Composing styles in a meaningful way reduces the amount of code duplication. |
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**Structure**: BEM gives your code a solid structure that is both easy to understand and to expand. |
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# References |
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- http://getbem.com/ |
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- https://csswizardry.com/2013/01/mindbemding-getting-your-head-round-bem-syntax/ |
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This is post 009 of [#100DaysToOffload](https://100daystooffload.com/). |