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Introduce “UnforgivingHtml” parser.
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Goals of the parser:
* Tighten control over things like double-quotes & closing tags.
* Improve error messaging for malformed markup.
* Improve performance.
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@theengineear
theengineear committed Dec 18, 2024
1 parent aaefbba commit e5c6421
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Showing 4 changed files with 1,211 additions and 74 deletions.
4 changes: 3 additions & 1 deletion test/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,9 @@ import '../x-template.js';

// Set a high bar for code coverage!
coverage(new URL('../x-element.js', import.meta.url).href, 100);
coverage(new URL('../x-template.js', import.meta.url).href, 100);

// TODO: Increase code coverage to 100 here.
coverage(new URL('../x-template.js', import.meta.url).href, 97);

test('./test-analysis-errors.html');
test('./test-initialization-errors.html');
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70 changes: 12 additions & 58 deletions test/test-template-engine.js
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ const localMessages = [
'Deprecated "unsafeSVG" from default templating engine interface.',
'Deprecated "repeat" from default templating engine interface.',
'Deprecated "map" from default templating engine interface.',
'Support for the "style" tag is deprecated and will be removed in future versions.',
];
console.warn = (...args) => { // eslint-disable-line no-console
if (!localMessages.includes(args[0]?.message)) {
Expand Down Expand Up @@ -654,18 +655,6 @@ describe('html rendering', () => {
assert(container.querySelector('textarea').value === 'foo');
});

it('title elements with no interpolation work', () => {
const container = document.createElement('div');
render(container, html`<title><em>this</em> is the &ldquo;default&rdquo; value</title>`);
assert(container.querySelector('title').textContent === '<em>this</em> is the “default” value');
});

it('title elements with strict interpolation work', () => {
const container = document.createElement('div');
render(container, html`<title>${'foo'}</title>`);
assert(container.querySelector('title').textContent === 'foo');
});

it('renders instantiated elements as dumb text', () => {
const getTemplate = ({ element }) => {
return html`${element}`;
Expand Down Expand Up @@ -775,24 +764,12 @@ describe('html rendering', () => {
#item = null;
set item(value) { updates.push(`outer-${value}`); this.#item = value; }
get item() { return this.#item; }
connectedCallback() {
// Prevent property shadowing by deleting before setting on connect.
const item = this.item ?? '???';
Reflect.deleteProperty(this, 'item');
Reflect.set(this, 'item', item);
}
}
customElements.define('test-depth-first-outer', TestDepthFirstOuter);
class TestDepthFirstInner extends HTMLElement {
#item = null;
set item(value) { updates.push(`inner-${value}`); this.#item = value; }
get item() { return this.#item; }
connectedCallback() {
// Prevent property shadowing by deleting before setting on connect.
const item = this.item ?? '???';
Reflect.deleteProperty(this, 'item');
Reflect.set(this, 'item', item);
}
}
customElements.define('test-depth-first-inner', TestDepthFirstInner);

Expand Down Expand Up @@ -1103,17 +1080,6 @@ describe('html errors', () => {
assertThrows(callback, expectedMessage);
});

it('throws when attempting to interpolate within a script tag', () => {
const evil = '\' + prompt(\'evil\') + \'';
const callback = () => html`
<script id="target">
console.log('${evil}');
</script>
`;
const expectedMessage = 'Interpolation of <script> tags is not allowed.';
assertThrows(callback, expectedMessage);
});

it('throws when attempting non-trivial interpolation of a textarea tag (preceding space)', () => {
const callback = () => html`<textarea id="target"> ${'foo'}</textarea>`;
const expectedMessage = 'Only basic interpolation of <textarea> tags is allowed.';
Expand All @@ -1138,24 +1104,6 @@ describe('html errors', () => {
assertThrows(callback, expectedMessage);
});

it('throws when attempting non-trivial interpolation of a title tag (preceding space)', () => {
const callback = () => html`<title> ${'foo'}</title>`;
const expectedMessage = 'Only basic interpolation of <title> tags is allowed.';
assertThrows(callback, expectedMessage);
});

it('throws when attempting non-trivial interpolation of a title tag (succeeding space)', () => {
const callback = () => html`<title>${'foo'} </title>`;
const expectedMessage = 'Only basic interpolation of <title> tags is allowed.';
assertThrows(callback, expectedMessage);
});

it('throws when attempting non-trivial interpolation of a title tag', () => {
const callback = () => html`<title>please ${'foo'} no</title>`;
const expectedMessage = 'Only basic interpolation of <title> tags is allowed.';
assertThrows(callback, expectedMessage);
});

it('throws when attempting non-trivial interpolation of a textarea tag via nesting', () => {
const callback = () => html`<textarea><b>please ${'foo'} no</b></textarea>`;
const expectedMessage = 'Only basic interpolation of <textarea> tags is allowed.';
Expand All @@ -1164,25 +1112,25 @@ describe('html errors', () => {

it('throws for unquoted attributes', () => {
const callback = () => html`<div id="target" not-ok=${'foo'}>Gotta double-quote those.</div>`;
const expectedMessage = 'Found invalid template on or after line 1 in substring `<div id="target" not-ok=`. Failed to parse ` not-ok=`.';
const expectedMessage = 'Seems like you have a malformed attribute — attribute names must be alphanumeric (both uppercase and lowercase is allowed), must not start or end with hyphens, and cannot start with a number — and, attribute values must be enclosed in double-quotes. See substring `not-ok=`. Your HTML was parsed through: `<div id="target" `.';
assertThrows(callback, expectedMessage);
});

it('throws for single-quoted attributes', () => {
const callback = () => html`\n<div id="target" not-ok='${'foo'}'>Gotta double-quote those.</div>`;
const expectedMessage = 'Found invalid template on or after line 2 in substring `\n<div id="target" not-ok=\'`. Failed to parse ` not-ok=\'`.';
const expectedMessage = 'Seems like you have a malformed attribute — attribute names must be alphanumeric (both uppercase and lowercase is allowed), must not start or end with hyphens, and cannot start with a number — and, attribute values must be enclosed in double-quotes. See substring `not-ok=\'`. Your HTML was parsed through: `\n<div id="target" `.';
assertThrows(callback, expectedMessage);
});

it('throws for unquoted properties', () => {
const callback = () => html`\n\n\n<div id="target" .notOk=${'foo'}>Gotta double-quote those.</div>`;
const expectedMessage = 'Found invalid template on or after line 4 in substring `\n\n\n<div id="target" .notOk=`. Failed to parse ` .notOk=`.';
const expectedMessage = 'Seems like you have a malformed property — property names must be alphanumeric (both uppercase and lowercase is allowed), must not start or end with underscores, and cannot start with a number — and, property values must be enclosed in double-quotes. See substring `.notOk=`. Your HTML was parsed through: `\n\n\n<div id="target" `.';
assertThrows(callback, expectedMessage);
});

it('throws for single-quoted properties', () => {
const callback = () => html`<div id="target" .notOk='${'foo'}'>Gotta double-quote those.</div>`;
const expectedMessage = 'Found invalid template on or after line 1 in substring `<div id="target" .notOk=\'`. Failed to parse ` .notOk=\'`.';
const expectedMessage = 'Seems like you have a malformed property — property names must be alphanumeric (both uppercase and lowercase is allowed), must not start or end with underscores, and cannot start with a number — and, property values must be enclosed in double-quotes. See substring `.notOk=\'`. Your HTML was parsed through: `<div id="target" `.';
assertThrows(callback, expectedMessage);
});

Expand Down Expand Up @@ -1309,6 +1257,12 @@ describe.todo('future html errors', () => {
assertThrows(callback, expectedMessage);
});

it('throws if there is other junk attached to the close tag', () => {
const callback = () => html`<div></div class="nope">`;
const expectedMessage = 'Seems like you have a malformed close tag — close tags must not contain any extraneous spaces or newlines and tag names must be alphanumeric, lowercase, cannot start or end with hyphens, and cannot start with a number. See substring `</div clas…`. Your HTML was parsed through: `<div>`.';
assertThrows(callback, expectedMessage);
});

it('throws if an unbound boolean attribute starts with a hyphen', () => {
const callback = () => html`<div -what></div>`;
const expectedMessage = 'Seems like you have a malformed attribute — attribute names must be alphanumeric (both uppercase and lowercase is allowed), must not start or end with hyphens, and cannot start with a number — and, attribute values must be enclosed in double-quotes. See substring `-what></di…`. Your HTML was parsed through: `<div `.';
Expand Down Expand Up @@ -1455,7 +1409,7 @@ describe.todo('future html errors', () => {

it('throws if you forget to close a tag', () => {
const callback = () => html`<div>`;
const expectedMessage = 'Did you forget a closing </div>? To avoid unintended markup, non-void tags must explicitly be closed.';
const expectedMessage = 'Did you forget a closing </div> at the very end of your template? To avoid unintended markup, non-void tags must explicitly be closed.';
assertThrows(callback, expectedMessage);
});

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2 changes: 1 addition & 1 deletion ts/x-template.d.ts.map
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