Throw a TypeError when appropriate.

6 years ago · c96c61a111
--- a/src/index.js
+++ b/src/index.js
@@ -2,6 +2,17 @@ export default function doctypeToString(doctype) {
    if (doctype === null) {
        return ''
    }
    // Checking with instanceof DocumentType might be neater, but how to get a
    // reference to DocumentType without assuming it to be available globally?
    // To play nice with custom DOM implementations, we resort to duck-typing.
    if (!doctype
        || doctype.nodeType !== doctype.DOCUMENT_TYPE_NODE
        || typeof doctype.name !== 'string'
        || typeof doctype.publicId !== 'string'
        || typeof doctype.systemId !== 'string'
    ) {
        throw new TypeError('Expected a DocumentType')
    }
    const doctypeString = `<!DOCTYPE ${doctype.name}`
        + (doctype.publicId ? ` PUBLIC "${doctype.publicId}"` : '')
        + (doctype.systemId
--- a/test/index.js
+++ b/test/index.js
@@ -17,6 +17,10 @@ test('should return empty string if doctype is null', t => {
    t.is(doctypeToString(null), '')
 })

 test('should throw if argument is not a DocumentType', t => {
    t.throws(() => doctypeToString('a string, for example.'), TypeError)
 })

 test('should work for a HTML5-ish doctype', t => {
    const doctype = '<!DOCTYPE html>'
    const doc = makeStubDocument(doctype)