BemjsonNode

BEM tree node representation.

Contents

• Install
• Usage
• API
• Serialization
• Debuggability

Install

$ npm install --save @bem/bemjson-node

Usage

const BemjsonNode = require('@bem/bemjson-node');

const bemjsonNode = new BemjsonNode({ block: 'button', elem: 'text' });

bemjsonNode.block;     // button
bemjsonNode.elem;      // text
bemjsonNode.mods;      // {}
bemjsonNode.elemMods;  // {}

API

• constructor({ block, mods, elem, elemMods, mix })
• block
• elem
• mods
• elemMods
• mix
• valueOf()
• toJSON()
• toString()
• static isBemjsonNode(bemjsonNode)

constructor({ block, mods, elem, elemMods, mix })

Parameter	Type	Description
block	string	The block name of entity.
mods	object	An object of modifiers for block entity. Optional.
elem	string	The element name of entity. Optional.
elemMods	object	An object of modifiers for element entity. Should not be used without elem field. Optional.
mix	string, object or array	An array of mixed bemjson nodes. From passed strings and objects will be created bemjson node objects. Optional.

const BemjsonNode = require('@bem/bemjson-node');

// The block with modifier
new BemjsonNode({
    block: 'button',
    mods: { view: 'action' }
});

// The element inside block with modifier
new BemjsonNode({
    block: 'button',
    mods: { view: 'action' },
    elem: 'inner'
});

// The element node with modifier
new BemjsonNode({
    block: 'button',
    elem: 'icon',
    elemMods: { type: 'load' }
});

// The block with a mixed element
new BemjsonNode({
    block: 'button',
    mix: { block: 'button', elem: 'text' }
});

// Invalid value in mods field
new BemjsonNode({
    block: 'button',
    mods: 'icon'
});
// ➜ AssertionError: @bem/bemjson-node: `mods` field should be a simple object or null.

block

The name of block to which entity in this node belongs.

const BemjsonNode = require('@bem/bemjson-node');
const name = new BemjsonNode({ block: 'button' });

name.block; // button

elem

The name of element to which entity in this node belongs.

Important: Contains null value if node is a block entity.

const BemjsonNode = require('@bem/bemjson-node');
const node1 = new BemjsonNode({ block: 'button' });
const node2 = new BemjsonNode({ block: 'button', elem: 'text' });

node1.elem; // null
node2.elem; // "text"

mods

The object with modifiers of this node.

Important: Contains modifiers of a scope (block) node if this node IS an element.

const BemjsonNode = require('@bem/bemjson-node');

const blockNode = new BemjsonNode({ block: 'button' });
const modsNode = new BemjsonNode({ block: 'button', mods: { disabled: true } });
const elemNode = new BemjsonNode({ block: 'button', mods: { disabled: true }, elem: 'text' });

blockNode.mods; // { }
elemNode.mods;  // { disabled: true }
modsNode.mods;  // { disabled: true }

elemMods

The object with modifiers of this node.

Important: Contains null if node IS NOT an element.

const BemjsonNode = require('@bem/bemjson-node');

const blockNode = new BemjsonNode({ block: 'button' });
const modsNode = new BemjsonNode({ block: 'button', mods: { disabled: true } });
const elemNode = new BemjsonNode({ block: 'button', elem: 'text' });
const emodsNode = new BemjsonNode({ block: 'button', elem: 'text', elemMods: { highlighted: true } });

blockNode.elemMods; // null
modsNode.elemMods;  // null
elemNode.elemMods;  // { }
emodsNode.elemMods; // { disabled: true }

valueOf()

Returns normalized object representing the bemjson node.

const BemjsonNode = require('@bem/bemjson-node');
const node = new BemjsonNode({ block: 'button', mods: { focused: true }, elem: 'text' });

node.valueOf();

// ➜ { block: 'button', mods: { focused: true }, elem: 'text', elemMods: { } }

toJSON()

Returns raw data for JSON.stringify() purposes.

const BemjsonNode = require('@bem/bemjson-node');

const node = new BemjsonNode({ block: 'input', mods: { available: true } });

JSON.stringify(node); // {"block":"input","mods":{"available":true}}

toString()

Returns string representing the bemjson node.

const BemjsonNode = require('@bem/bemjson-node');
const node = new BemjsonNode({
    block: 'button', mods: { focused: true },
    mix: { block: 'mixed', mods: { bg: 'red' } }
});

node.toString(); // "button _focused  mixed _bg_red"

static isBemjsonNode(bemjsonNode)

Determines whether specified object is an instance of BemjsonNode.

Parameter	Type	Description
bemjsonNode	*	The object to check.

const BemjsonNode = require('@bem/bemjson-node');

const bemjsonNode = new BemjsonNode({ block: 'input' });

BemjsonNode.isBemjsonNode(bemjsonNode); // true
BemjsonNode.isBemjsonNode({ block: 'button' }); // false

Serialization

The BemjsonNode has toJSON method to support JSON.stringify() behaviour.

Use JSON.stringify to serialize an instance of BemjsonNode.

const BemjsonNode = require('@bem/bemjson-node');

const node = new BemjsonNode({ block: 'input', mod: 'available' });

JSON.stringify(node); // {"block":"input","mods":{"available":true}}

Use JSON.parse to deserialize JSON string and create an instance of BemjsonNode.

const BemjsonNode = require('@bem/bemjson-node');

const str = '{"block":"input","mods":{"available"::true}}';

new BemjsonNode(JSON.parse(str)); // BemjsonNode({ block: 'input', mods: { available: true } });

Debuggability

In Node.js, console.log() calls util.inspect() on each argument without a formatting placeholder.

BemjsonNode has inspect() method to get custom string representation of the object.

const BemjsonNode = require('@bem/bemjson-node');

const node = new BemjsonNode({ block: 'input', mods: { available: true } });

console.log(node);

// ➜ BemjsonNode { block: 'input', mods: { available: true } }

You can also convert BemjsonNode object to string.

const BemjsonNode = require('@bem/bemjson-node');

const node = new BemjsonNode({ block: 'input', mods: { available: true } });

console.log(`node: ${node}`);

// ➜ node: input _available

License

Code and documentation © 2017 YANDEX LLC. Code released under the Mozilla Public License 2.0.