Apply vue-katex to content loaded from static folder - vue.js

Question

I'm trying to make a blog using Vue as laid out in the excellent demo here. I'd like to include some mathematical formulas and equations in my blog, so I thought I'd try to use vue-katex. vue-katex formats my mathematical notation perfectly when I put all my KaTeX HTML directly into my Vue templates, but to create a useable blog I need to keep my content separate from my templates (as shown in the demo).
I can't get vue-katex to format HTML content in the static folder. That's what I'd like help with.
Setup
I cloned the github repo for the demo.
I added vue-katex to package.json:
"vue-katex": "^0.1.2",
I added the KaTeX CSS to index.html:
<!-- KaTeX styles -->
<link
rel="stylesheet"
href="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.9.0-alpha2/katex.min.css"
integrity="sha384-exe4Ak6B0EoJI0ogGxjJ8rn+RN3ftPnEQrGwX59KTCl5ybGzvHGKjhPKk/KC3abb"
crossorigin="anonymous"
>
I added the import statement to src/App.vue:
import Vue from 'vue'
import VueKatex from 'vue-katex'
Vue.use(VueKatex)
and I added a simple line of HTML with KaTeX to the BlogPost template:
<p>Here's an equation in the actual Vue template: <div class="equation" v-katex="'X \\sim N(\\mu, \\sigma^2)'"></div></p>
As I said, this works - I see formatted mathematical notation in my blog post (URL http://localhost:8080/read/neque-libero-convallis-eget):
However, I need different equations for every blog post, of course.
So I tried adding KaTeX HTML to the "content" field in the JSON for the first blog post: static/api/post/neque-libero-convallis-eget.json. I changed the "content" line to:
"content": "Here's an equation in the static folder: <div class=\"equation\" v-katex=\"'X \\sim N(\\mu, \\sigma^2)'\"></div>",
This content appears on the page, but the equation doesn't render. I see this: (the text appears but no equation is shown)
When I use Developer Tools to inspect the HTML on the page, I see this:
You can see that vue-katex has been applied to the equation I put in the template directly: it has parsed the HTML I typed into lots of spans with all the mathematical symbols, which are showing perfectly.
However the KaTeX HTML I've added to the "content" in the static folder has simply been placed on the page exactly as I typed it, and is therefore not showing up as an equation on the page. I really need to keep my blog post content in this static folder - I don't want to have to create a different .vue file for each blog post, that defeats the point!
My question is: is there a way to manually "apply" vue-katex to the HTML I place in the static folder, when it loads? Perhaps there is something I can add to the plugins/resource/index.js file, since this contains the function that loads the data from the static folder?
Many thanks in advance for any help.

Answer 1

*Disclaimer: I'm definitely no expert / authority on what I'm about to explain!
One thing to remember is that Vue reads the templates you write, and then replaces them as reactive components. This means that although you often write Vue attributes like v-for, v-html or in this case v-katex these attributes are only useful up until the app or component is mounted.
With this in mind, if you have a Vue app that ajax loads some html, its not going to be able to rerender itself with those Vue bindings in place.
I have somewhat ignored your current set up and set about solving the issue in another way.
Step 1: Reformat your data from the server side
I've put the posts into an array, and each post contains the template (just a string of html) and the equations separately as an array. I've used [e1] in the post as a placeholder for where the katex will go.
var postsFromServer = [{
content : `<div>
<h2>Crazy equation</h2>
<p>Look here!</p>
[e1]
</div>`,
equations : [
{
key : 'e1',
value : "c = \\pm\\sqrt{a^2 + b^2}"
}
]
}];
Step 2: When the post is rendered, do some work on it
Rather than just use v-html="post.content", I've wrapped the html output in a method
<div id="app">
<div v-for="post in posts" v-html="parsePostContent(post)">
</div>
</div>
Step 3: Create a method that renders all the katex, and then replaces the placeholders in the post
methods : {
parsePostContent(post){
// Loop through every equation that we have in our post from the server
for(var e = 0; e < post.equations.length; e++){
// Get the raw katex text
var equation = post.equations[e].value;
// Get the placeholder i.e. e1
var position = post.equations[e].key;
// Replace [e1] in the post content with the rendered katex
post.content = post.content.replace("[" + position + "]", katex.renderToString(equation));
}
// Return
return post.content;
}
}
Here is the whole set up, which renders Katex:
https://codepen.io/EightArmsHQ/pen/qxzEQP?editors=1010