VisitorNodeMap

at rule visitor

Example: change media at-rule prelude

import {transform, AstAtRule, ParserOptions} from "@tbela99/css-parser";

const options: ParserOptions = {

    visitor: {

        AtRule: {

            media: (node: AstAtRule): AstAtRule => {

                node.val = 'tv,screen';
                return node
            }
        }
    }
};

const css = `

@media screen {

    .foo {

            height: calc(100px * 2/ 15);
    }
}
`;

const result = await transform(css, options);

console.debug(result.code);

// @media tv,screen{.foo{height:calc(40px/3)}}
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declaration visitor

Example: add 'width: 3px' everytime a declaration with the name 'height' is found

import {transform, parseDeclarations} from "@tbela99/css-parser";

const options: ParserOptions = {

    removeEmpty: false,
    visitor: {

        Declaration: {

            // called only for height declaration
            height: (node: AstDeclaration): AstDeclaration[] => {


                return [
                    node,
                    {

                        typ: EnumToken.DeclarationNodeType,
                        nam: 'width',
                        val: [
                            <LengthToken>{
                                typ: EnumToken.LengthTokenType,
                                val: 3,
                                unit: 'px'
                            }
                        ]
                    }
                ];
            }
           }
        }
};

const css = `

.foo {
    height: calc(100px * 2/ 15);
}
.selector {
color: lch(from peru calc(l * 0.8) calc(c * 0.7) calc(h + 180))
}
`;

console.debug(await transform(css, options));

// .foo{height:calc(40px/3);width:3px}.selector{color:#0880b0}
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Example: rename 'margin' to 'padding' and 'height' to 'width'

import {AstDeclaration, ParserOptions, transform} from "../src/node.ts";

const options: ParserOptions = {

    visitor: {

        // called for every declaration
        Declaration: (node: AstDeclaration): null => {


            if (node.nam == 'height') {

                node.nam = 'width';
            }

            else if (node.nam == 'margin') {

                node.nam = 'padding'
            }

            return null;
        }
    }
};

const css = `

.foo {
    height: calc(100px * 2/ 15);
    margin: 10px;
}
.selector {

margin: 20px;}
`;

const result = await transform(css, options);

console.debug(result.code);

// .foo{width:calc(40px/3);padding:10px}.selector{padding:20px}
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rule visitor

Example: add 'width: 3px' to every rule with the selector '.foo'

import {transform, parseDeclarations} from "@tbela99/css-parser";

const options: ParserOptions = {

    removeEmpty: false,
    visitor: {

        Rule: async (node: AstRule): Promise<AstRule | null> => {

            if (node.sel == '.foo') {

                node.chi.push(...await parseDeclarations('width: 3px'));
                return node;
            }

            return null;
        }
    }
};

const css = `

.foo {
    .foo {
    }
}
`;

console.debug(await transform(css, options));

// .foo{width:3px;.foo{width:3px}}
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value visitor