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* Wrap `katex.render` examples with try...catch * Add starter template with defer in README.md * Update documentation to use `defer` and `onload` * Add documentation on async and pre loading KaTeX * Use sha384 for SRI * Revise wording according to comments * Minor changes * Fix article
36 lines
1.3 KiB
Markdown
36 lines
1.3 KiB
Markdown
---
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id: error
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title: Handling Errors
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---
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If KaTeX encounters an error (invalid or unsupported LaTeX) and `throwOnError`
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hasn't been set to `false`, then `katex.render` and `katex.renderToString`
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will throw an exception of type `katex.ParseError`.
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The message in this error includes some of the LaTeX source code,
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so needs to be escaped if you want to render it to HTML. For example:
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```js
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try {
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var html = katex.renderToString(texString);
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// '<span class="katex">...</span>'
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} catch (e) {
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if (e instanceof katex.ParseError) {
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// KaTeX can't parse the expression
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html = ("Error in LaTeX '" + texString + "': " + e.message)
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.replace(/&/g, "&").replace(/</g, "<").replace(/>/g, ">");
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} else {
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throw e; // other error
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}
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}
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```
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In particular, you should convert `&`, `<`, `>` characters to
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`&`, `<`, `>` before including either LaTeX source code or
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exception messages in your HTML/DOM.
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(This can also be done using `_.escape`.)
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Failure to escape in this way makes a `<script>` injection attack possible
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if your LaTeX source is untrusted.
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Alternatively, you can set `throwOnError` to `false` to use built-in behavior
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of rendering the LaTeX source code with hover text stating the error.
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See [rendering options](options.md).
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