insertBefore

const insertBefore: (grammar, before, insert) => void

Defined in: prism/utils/language.d.ts:54

Inserts tokens before another token in the given grammar.

Usage

This helper method makes it easy to modify existing grammars. For example, the markup language definition defines highlighting for CSS embedded in HTML through <style> elements. To do this, it needs to modify languages.markup and add the appropriate tokens. However, languages.markup is a regular JavaScript object literal, so if you do this:

markup.style = {
 // token
};

then the style token will be added (and processed) at the end. insertBefore allows you to insert tokens before existing tokens. For the markup example above, you would use it like this:

insertBefore(markup, 'cdata', {
 'style': {
 // token
 }
});

Special cases

If the grammars of grammar and insert have tokens with the same name, the tokens in grammar’s grammar will be ignored.

This behavior can be used to insert tokens after before:

insertBefore(markup, 'comment', {
 'comment': markup.comment,
 // tokens after 'comment'
});

Parameters

grammar

Grammar

The grammar to be modified.

before

TokenName

The key to insert before.

insert

GrammarTokens

An object containing the key-value pairs to be inserted.

Returns

void