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BEMHTML source code converter:

  • old syntax to new JS-syntax (-f bemxjst1)
  • old syntax to new JS-syntax compatible with bem-xjst4 (-f bemxjst4)
  • old syntax to BH (exposes bemhtml-source-convert functionality)

Given the impedence mismatch between Bemhtml and Bh it does not seem possible to convert every template or guarantee that the applicative semantics of the source is preserved in the result. Bemhtml is much too expressive and lenient to deliver on such promise. The ability to apply templates in a modified context powered by xjst methods apply, applyNext, applyCtx employing the result is one feature prominantly missing in Bh. Its applyBase method carries a very particular meaning that doesn't map clearly on Bemhtml machinery and as of this writing appears to be broken anyway.


npm -g install bemhtml-syntax


bemhtml-syntax [OPTIONS] [ARGS]
# convert to new JS-syntax (bemxjst4 is the default and -f can be dropped). 
# -f bemxjst4 will also do its best to preserve comments. 
bemhtml-syntax -f bemxjst4 [OPTIONS] [ARGS]
# convert to BH 
bemhtml-syntax -f bh [OPTIONS] [ARGS]

-S flag aka --strictOff is specific to BH converter and as the name suggests turns the default strict compiler mode off. Generally we don't recommend it, but this may help you convert many more templates to BH without warnings so it's there for when you have a fairly big BEMHTML template you want to convert to BH and you'd rather have some skeleton you can flesh out rather than starting completely from scratch. The result is not guaranteed to carry proper BEMHTML semantics over to BH and assumes that you'll fix it by hand.

Other options mostly control the code-style of generated code. E.g. you may prefer -q double quotes for strings and enforcing -Q quotes around object keys, etc. Converter also accepts most options offered by js-beautify.

For example, convert

block b-wrapper {
    tag: 'wrap'
    content: this.ctx.content
block b-inner, default: applyCtx({ block: 'b-wrapper', content: this.ctx.content })

with bemhtml-syntax -f bemxjst1 -q "double" -Q -i test/basic/info6.bemhtml into

    content()(function() {
        return this.ctx.content
block("b-inner").def()(function() {
    return applyCtx({
        "block": "b-wrapper",
        "content": this.ctx.content


var syntax = require('bemhtml-syntax'),
    source = 'block b1, tag: "a"',
    options = { indent_size: 2 };
// Parse BEMHTML code 
// bemxjst1 
var ast = syntax.parse(source);
// bemxjst4 
var ast = syntax.kparse(source);
// Transform AST for serialisation 
// bemxjst1 
var newAst = syntax.translate(ast);
// bemxjst4 
var newAst = syntax.ktranslate(ast);
// Serialise to JavaScript 
// bemxjst1 
var jsCode1 = syntax.generate(newAst, options);
// bemxjst4 
var jsCode1 = syntax.kgenerate(newAst, options);
// Or do everything in one go 
// bemxjst1 
var jsCode2 = syntax.compile(source, options);
// bemxjst4 
var jsCode2 = syntax.kcompile(source, options);
// BH converter (see notes in [bemhtml-source-convert] repo) 
var bhStxConstructor = syntax.getBhConstructor(),
    stx = new bhStxConstructor(source, options);

Added in the latest version are some bem-xjst4 specific features, these will work only with -f bemxjst4:

  -eM, --elem-match : Wrap predicates with "this.elem" in "elemMatch" (default: false)
  -wP, --wrap-pattern : Use "wrap()" instead of "def()+applyCtx()+this.ctx()" pattern  (default: false)
  -aB, --assert-has-block : Assert that every template has sub-predicate matching "block"  (default: false)
  -aE, --assert-no-this-elem : Assert "this.elem" is not used in predicates (default: false)
  -aF, --assert-no-buf : Assert "this._buf" is not used in templates (default: false)
  -rD, --return-from-def : Always return in "default" mode, insert "return ''" when missing. (default: false)
  -aM, --apply-sets-mode : Assert that every call to apply() sets a mode in its 1st argument. (default: false)
  -aC, --apply-check-fields : Warn if apply() sets any of "block""elem""mods" or "elemMods"(default: false)