bem-naming

bem-naming

About

This tool allows getting information about BEM-entity using string as well as forming string representation based on BEM-naming.

String representation

To define BEM-entities we often use a special string format that allows us 100% define what entity exactly is represented.

According to original BEM-naming convention it looks like the following:

'block[_block-mod-name[_block-mod-val]][__elem-name[_elem-mod-name[_elem-mod-val]]]'

(Parameters whithin square brackets are optional)

• Block — block-name.
• Block's modifier in key-value format — block-name_mod-name_mod-val.
• Block's boolean modifier — block-name_mod.
• Block's element — block-name__elem-name.
• Element's modifier in key-value format — block-name__elem-name_mod-name_mod-val.
• Element's boolean modifier — block-name__elem_mod.

Common misconceptions

BEM methodology involves the use of flat structure inside a block. It means that BEM entity can not be represented as an element of the other element and the following string representation will be invalid:

'block__some-elem__sub-elem'

Also there is no such BEM entity as a modifier and an element modifier simultaneously so the following string representation will be invalid:

'block_block-mod-name_block-mod-val__elem-name_elem-mod-name_elem-mod-val'

BEM-naming

BEM-entities can be defined with a help of js-object with the following fields:

• block — block's name. The field is required because block is the only independent BEM-entity.
• elem — element's name.
• modName — modifier's name.
• modVal — modifier's value.

API

• validate(str)
• parse(str)
• stringify(obj)
• isBlock(str)
• isBlock(obj)
• isBlockMod(str)
• isBlockMod(obj)
• isElem(str)
• isElem(obj)
• isElemMod(str)
• isElemMod(obj)

validate(str)

Checks a string to be valid BEM notation.

Example:

bemNaming.validate('block-name');  // true
bemNaming.validate('^*^');         // false

---

parse(str)

It parses string str into BEM-naming.

Example:

bemNaming.parse('block__elem_mod_val');  // { block: 'block', elem: 'elem',
                                         //   modName: 'mod', modVal: 'val' }

---

stringify(obj)

It forms a string according to BEM-naming obj.

Example:

bemNaming.stringify({
    block: 'block', elem: 'elem',
    modName: 'mod', modVal: 'val'
}); // 'block__elem_mod_val'

---

isBlock(str)

Checks whether string str is a block.

Example:

bemNaming.isBlock('block-name');   // true
bemNaming.isBlock('block__elem');  // false

---

isBlock(obj)

Checks whether BEM-naming obj is a block.

Example:

bemNaming.isBlock({ block: 'block-name' });           // true
bemNaming.isBlock({ block: 'block', elem: 'elem' });  // false

---

isBlockMod(str)

Checks whether string str is modifier of a block.

Example:

bemNaming.isBlockMod('block_mod');        // true
bemNaming.isBlockMod('block__elem_mod');  // false

---

isBlockMod(obj)

Checks whether BEM-naming obj is modifier of a block.

Example:

bemNaming.isBlockMod({ block: 'block',
    modName: 'mod', modVal: true });  // true

bemNaming.isBlockMod({ block: 'block', elem: 'elem',
    modName: 'mod', modVal: true });  // false

---

isElem(str)

Checks whether string str is element of a block.

Example:

bemNaming.isElem('block__elem');  // true
bemNaming.isElem('block-name');   // false

---

isElem(obj)

Checks whether BEM-naming obj is element of a block.

Example:

bemNaming.isElem({ block: 'block', elem: 'elem' });  // true
bemNaming.isElem({ block: 'block-name' });           // false

---

isElemMod(str)

Checks whether string str is modifier of an element.

Example:

bemNaming.isElemMod('block__elem_mod');  // true
bemNaming.isElemMod('block__elem');      // false

---

isElemMod(obj)

Checks whether BEM-naming obj is modifier of an element.

Example:

bemNaming.isElemMod({ block: 'block', elem: 'elem',
    modName: 'mod', modVal: true });  // true

bemNaming.isElemMod({ block: 'block',
    modName: 'mod', modVal: true});   // false

Custom naming convention

To use your own naming convention to define strings that represent BEM-entities we need to create instance of BEMNaming-class.

Constructor BEMNaming gets the object from the following options:

• String modSeparator — separates names and values of modifiers from blocks and elements. Default as _.
• String elemSeparator — separates element's name from block. Default as __.
• String literal — defines which symbols can be used for block, element and modifier's names. Default as [a-zA-Z0-9-].

Example:

var BEMNaming = bemNaming.BEMNaming;
var myNaming = new BEMNaming({
    elemSeparator: '-',
    modSeparator: '--',
    literal: '[a-zA-Z0-9]'        // because element and modifier's separators include
});                               // hyphen in it, we need to exclude it from block,
                                  // element and modifier's name
                                
myNaming.parse('block--mod');     // { block: 'block',
                                  //   modName: 'mod', modVal: true }

myNaming.stringify({              // 'blockName-elemName--boolElemMod'
    block: 'blockName',
    elem: 'elemName',
    modName: 'boolElemMod'
});