s0rg/crawley

package links

import (
    "bytes"
    "io"
    "strings"

    "github.com/tdewolff/parse/v2"
    "github.com/tdewolff/parse/v2/js"
)

const (
    codeCleanChars = `"'`
    dash           = "/"
    doubleDash     = dash + dash
)

// ExtractJS extract urls from js files.
func ExtractJS(r io.Reader, h URLHandler) {
    l := js.NewLexer(parse.NewInput(r))

    for {
        tt, text := l.Next()
        switch tt {
        case js.ErrorToken:
            return
        case js.StringToken:
            if res, ok := extractJSURL(text); ok {
                h(res)
            }
        }
    }
}

func extractJSURL(v []byte) (rv string, ok bool) {
    rv = string(bytes.Trim(v, codeCleanChars))
    ok = strings.HasPrefix(rv, dash) || strings.Contains(rv, doubleDash)

    return rv, ok
}