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Performance improvements! #192

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merged 2 commits into from
Mar 25, 2021
Merged

Performance improvements! #192

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b6aa5a7
Performance improvements!
developit Mar 20, 2021
95e4bc8
Reintroduce Fragment optimization
developit Mar 25, 2021
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73 changes: 35 additions & 38 deletions src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,9 @@ import {
assign,
getChildren
} from './util';
import { options, Fragment, createElement } from 'preact';
import { options } from 'preact';

/** @typedef {import('preact').VNode} VNode */

const SHALLOW = { shallow: true };

Expand All @@ -28,7 +30,7 @@ const noop = () => {};
* @param {Boolean} [options.shallow=false] If `true`, renders nested Components as HTML elements (`<Foo a="b" />`).
* @param {Boolean} [options.xml=false] If `true`, uses self-closing tags for elements without children.
* @param {Boolean} [options.pretty=false] If `true`, adds whitespace for readability
* @param {RegEx|undefined} [options.voidElements] RegeEx that matches elements that are considered void (self-closing)
* @param {RegExp|undefined} [options.voidElements] RegeEx that matches elements that are considered void (self-closing)
*/
renderToString.render = renderToString;

Expand All @@ -43,6 +45,8 @@ let shallowRender = (vnode, context) => renderToString(vnode, context, SHALLOW);

const EMPTY_ARR = [];
function renderToString(vnode, context, opts) {
context = context || {};
opts = opts || {};
const res = _renderToString(vnode, context, opts);
// options._commit, we don't schedule any effects in this library right now,
// so we can pass an empty queue to this hook.
Expand All @@ -56,48 +60,40 @@ function _renderToString(vnode, context, opts, inner, isSvgMode, selectValue) {
return '';
}

// #text nodes
if (typeof vnode !== 'object') {
return encodeEntities(vnode);
}

let pretty = opts.pretty,
indentChar = pretty && typeof pretty === 'string' ? pretty : '\t';

// wrap array nodes in Fragment
if (Array.isArray(vnode)) {
vnode = createElement(Fragment, null, vnode);
let rendered = '';
for (let i = 0; i < vnode.length; i++) {
if (pretty && i > 0) rendered += '\n';
rendered += _renderToString(
vnode[i],
context,
opts,
inner,
isSvgMode,
selectValue
);
}
return rendered;
}

let nodeName = vnode.type,
props = vnode.props,
isComponent = false;
context = context || {};
opts = opts || {};

let pretty = opts.pretty,
indentChar = pretty && typeof pretty === 'string' ? pretty : '\t';

// #text nodes
if (typeof vnode !== 'object' && !nodeName) {
return encodeEntities(vnode);
}

// components
if (typeof nodeName === 'function') {
isComponent = true;
if (opts.shallow && (inner || opts.renderRootComponent === false)) {
nodeName = getComponentName(nodeName);
} else if (nodeName === Fragment) {
let rendered = '';
let children = [];
getChildren(children, vnode.props.children);

for (let i = 0; i < children.length; i++) {
rendered +=
(i > 0 && pretty ? '\n' : '') +
_renderToString(
children[i],
context,
opts,
opts.shallowHighOrder !== false,
isSvgMode,
selectValue
);
}
return rendered;
} else {
let rendered;

Expand Down Expand Up @@ -197,7 +193,7 @@ function _renderToString(vnode, context, opts, inner, isSvgMode, selectValue) {
}

// render JSX to HTML
let s = '',
let s = '<' + nodeName,
propChildren,
html;

Expand All @@ -215,7 +211,7 @@ function _renderToString(vnode, context, opts, inner, isSvgMode, selectValue) {
continue;
}

if (name.match(/[\s\n\\/='"\0<>]/)) continue;
if (UNSAFE_NAME.test(name)) continue;

if (
!(opts && opts.allAttributes) &&
Expand Down Expand Up @@ -287,18 +283,19 @@ function _renderToString(vnode, context, opts, inner, isSvgMode, selectValue) {

// account for >1 multiline attribute
if (pretty) {
let sub = s.replace(/^\n\s*/, ' ');
let sub = s.replace(/\n\s*/, ' ');
if (sub !== s && !~sub.indexOf('\n')) s = sub;
else if (pretty && ~s.indexOf('\n')) s += '\n';
}

s = `<${nodeName}${s}>`;
if (UNSAFE_NAME.test(String(nodeName)))
s += '>';

if (UNSAFE_NAME.test(nodeName))
throw new Error(`${nodeName} is not a valid HTML tag name in ${s}`);

let isVoid =
VOID_ELEMENTS.test(String(nodeName)) ||
(opts.voidElements && opts.voidElements.test(String(nodeName)));
VOID_ELEMENTS.test(nodeName) ||
(opts.voidElements && opts.voidElements.test(nodeName));
let pieces = [];

let children;
Expand Down
15 changes: 5 additions & 10 deletions src/util.js
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Original file line number Diff line number Diff line change
@@ -1,17 +1,12 @@
// DOM properties that should NOT have "px" added when numeric
export const IS_NON_DIMENSIONAL = /acit|ex(?:s|g|n|p|$)|rph|grid|ows|mnc|ntw|ine[ch]|zoo|^ord|^--/i;

const HTML_ENTITY_REG = /[&<>"]/g;
const tagsToReplace = {
'&': '&amp;',
'<': '&lt;',
'>': '&gt;',
'"': '&quot;'
};
const replaceTag = (tag) => tagsToReplace[tag] || tag;
export function encodeEntities(s) {
if (typeof s !== 'string') s = String(s);
return s.replace(HTML_ENTITY_REG, replaceTag);
return String(s)
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@marvinhagemeister marvinhagemeister Mar 20, 2021 •
edited
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Let's add a comment to summarize our findings from yesterdays quick benchmarking session and why we're going with the replace variant again.

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I've always felt that this change was suspicious and could be the root cause of the performance issues I reported previously for versions after 5.1.2.

I plan to deploy a test release next Monday and roll back this part of the change separately from the 5.1.16 version of the code to see if there are still performance issues.

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@JimLiu JimLiu Mar 24, 2021 •
edited
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FYI https://jsben.ch/hR6XD
image

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@developit developit Mar 25, 2021 •
edited
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@JimLiu - that benchmark website produces statistically meaningless results. It's not open source (which is a problem), but I looked at the implementation and it's effectively running benchmarks in a tight loop: while(performance.now()-start < 5000) test(). This makes the order of benchmarks matter, and allows the JS VM to perform cross-benchmark optimizations that can only happen in the specific case of while(1) test() and never in real code.

The only current benchmarking website that produces statistically meaningful results is ESbench (disclaimer: I maintain it). The reason for this is because it uses the same Benchmark.js (the library that powered JSPerf, built by Matthias Bynens from the V8 team). Benchmark.js performs JIT warmup runs, encapsulates benchmarks in functions that prevent synthetic VM optimizations (like hoisting/inlining of benchmark code), and returns median values with standard deviation.

Here's the benchmarks we use for encodeEntities on ESBench:
https://esbench.com/bench/5f88af6cb4632100a7dcd414

Screen Shot 2021-03-25 at 11 45 36 AM

.replace(/&/g, '&amp;')
.replace(/</g, '&lt;')
.replace(/>/g, '&gt;')
.replace(/"/g, '&quot;');
}

export let indent = (s, char) =>
Expand Down