id | title |
---|---|
error |
Handling Errors |
If KaTeX encounters an error (invalid or unsupported LaTeX) and throwOnError
hasn't been set to false
, then katex.render
and katex.renderToString
will throw an exception of type katex.ParseError
.
The message in this error includes some of the LaTeX source code,
so needs to be escaped if you want to render it to HTML. For example:
try {
var html = katex.renderToString(texString);
// '<span class="katex">...</span>'
} catch (e) {
if (e instanceof katex.ParseError) {
// KaTeX can't parse the expression
html = ("Error in LaTeX '" + texString + "': " + e.message)
.replace(/&/g, "&").replace(/</g, "<").replace(/>/g, ">");
} else {
throw e; // other error
}
}
In particular, you should convert &
, <
, >
characters to
&
, <
, >
before including either LaTeX source code or
exception messages in your HTML/DOM.
(This can also be done using _.escape
.)
Failure to escape in this way makes a <script>
injection attack possible
if your LaTeX source is untrusted.
Alternatively, you can set throwOnError
to false
to use built-in behavior
of rendering the LaTeX source code with hover text stating the error.
See rendering options.