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Decorations

We provide a decorations API allowing you to warp custom class and attributes to ranges of your code.

ts
import { 
codeToHtml
} from 'shiki'
const
code
= `
const x = 10 console.log(x) `.
trim
()
const
html
= await
codeToHtml
(
code
, {
theme
: 'vitesse-light',
lang
: 'ts',
decorations
: [
{ // line and character are 0-indexed
start
: {
line
: 1,
character
: 0 },
end
: {
line
: 1,
character
: 11 },
properties
: {
class
: 'highlighted-word' }
} ] })

The result will be (styled with CSS in this example):

ts
const x = 10
console.log(x)

The positions can also be 0-indexed offsets relative to the code:

ts
const 
html
= await
codeToHtml
(
code
, {
theme
: 'vitesse-light',
lang
: 'ts',
decorations
: [
{
start
: 21,
end
: 24,
properties
: {
class
: 'highlighted-word' }
} ] })

It renders:

ts
const x = 10
console.log(x)

Use Decorations in Transformers

For advanced use cases, you can use the Transformers API to have full access to the tokens and the HAST tree.

Meanwhile, if you want to append decorations within a transformer, you can do that with:

ts
import { ShikiTransformer, 
codeToHtml
} from 'shiki'
const
myTransformer
: ShikiTransformer = {
name
: 'my-transformer',
preprocess
(
code
,
options
) {
// Generate the decorations somehow const
decorations
=
doSomethingWithCode
(
code
)
// Make sure the decorations array exists
options
.
decorations
||= []
// Append the decorations
options
.
decorations
.
push
(...
decorations
)
} } const
html
= await
codeToHtml
(
code
, {
theme
: 'vitesse-light',
lang
: 'ts',
transformers
: [
myTransformer
] })

Note that you can only provide decorations in or before the preprocess hook. In later hooks, changes to the decorations arrary will be ignored.

Released under the MIT License.