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Recover MathJax from Math Processing Errors 

closes LS-2105
flag=new_math_equation_handling

This change adds a math processing error handler that will remove
offending the MathJax output.

test plan:
  - i have no idea how to trigger the error. All I know is that
    it worked on
    https://coastdistrict.instructure.com/courses/79832/discussion_topics/835725

Change-Id: Ifbf763b51733ea0f7622975a4d902bb9d3fb6ef7
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/262142
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Nate Armstrong <narmstrong@instructure.com>
QA-Review: Nate Armstrong <narmstrong@instructure.com>
Product-Review: Nate Armstrong <narmstrong@instructure.com>
This commit is contained in:
Ed Schiebel 2021-04-01 19:10:22 -04:00 committed by Nate Armstrong
parent 19ed7c0c5c
commit 5d8632bb84
1 changed files with 34 additions and 11 deletions
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35
public/javascripts/mathml.js
View File

@ -65,6 +65,20 @@ const mathml = {
window.MathJax.Hub.Register.MessageHook('Begin PreProcess', function (message) {
mathImageHelper.catchEquationImages(message[1])
})
window.MathJax.Hub.Register.MessageHook('Math Processing Error', function (message) {
const elem = message[1]
// ".math_equation_latex" is the elem we added for MathJax to typeset the image equation
if (elem.parentElement?.classList.contains('math_equation_latex')) {
// The equation we image we were trying to replace and failed is up 1 and back 1.
// If we remove its "mathjaxified" attribute, the "End Math" handler
// won't remove it from the DOM.
if (elem.parentElement.previousElementSibling?.hasAttribute('mathjaxified')) {
elem.parentElement.previousElementSibling.removeAttribute('mathjaxified')
}
// remove the "math processing error" mathjax output.
elem.parentElement.remove()
}
})
window.MathJax.Hub.Register.MessageHook('End Math', function (message) {
mathImageHelper.removeStrayEquationImages(message[1])
message[1]
@ -149,26 +163,35 @@ const mathml = {
return false
},
mathJaxGenerated: /^MathJax|MJX/,
// elements to ignore selector
ignore_list: '#header,#mobile-header,#left-side,#quiz-elapsed-time,.ui-menu-carat',
isMathJaxIgnored(elem) {
if (!elem) return true
// ignore disconnected elements
if (!document.body.contains(elem)) return true
// elements to ignore selector
const ignore_list =
'.MJX_Assistive_MathML,#header,#mobile-header,#left-side,#quiz-elapsed-time,.ui-menu-carat'
// check if elem is in the ignore list
if (elem.parentElement?.querySelector(ignore_list) === elem) {
if (elem.parentElement?.querySelector(this.ignore_list) === elem) {
return true
}
// check if elem is a child of .mathjax_ignore
// check if elem is a child of something we're ignoring
while (elem !== document.body) {
// child of .mathjax_ignore?
if (elem.classList.contains('mathjax_ignore')) {
return true
}
// child of MathJax generated element?
if (
this.mathJaxGenerated.test(elem.id) ||
this.mathJaxGenerated.test(elem.getAttribute('class'))
) {
return true
}
elem = elem.parentElement
}
return false