添加了正确的katex方法

static/katex/contrib/copy-tex.min.js

@@ -0,0 +1 @@
+!function(e,t){if("object"==typeof exports&&"object"==typeof module)module.exports=t();else if("function"==typeof define&&define.amd)define([],t);else{var n=t();for(var o in n)("object"==typeof exports?exports:e)[o]=n[o]}}("undefined"!=typeof self?self:this,(function(){return function(){"use strict";var e={};const t={inline:["$","$"],display:["$$","$$"]};var n=function(e,n){void 0===n&&(n=t);const o=e.querySelectorAll(".katex-mathml + .katex-html");for(let e=0;e<o.length;e++){const t=o[e];t.remove?t.remove():t.parentNode&&t.parentNode.removeChild(t)}const r=e.querySelectorAll(".katex-mathml");for(let e=0;e<r.length;e++){const t=r[e],o=t.querySelector("annotation");o&&(t.replaceWith?t.replaceWith(o):t.parentNode&&t.parentNode.replaceChild(o,t),o.innerHTML=n.inline[0]+o.innerHTML+n.inline[1])}const l=e.querySelectorAll(".katex-display annotation");for(let e=0;e<l.length;e++){const t=l[e];t.innerHTML=n.display[0]+t.innerHTML.substr(n.inline[0].length,t.innerHTML.length-n.inline[0].length-n.inline[1].length)+n.display[1]}return e};function o(e){const t=e instanceof Element?e:e.parentElement;return t&&t.closest(".katex")}return document.addEventListener("copy",(function(e){const t=window.getSelection();if(t.isCollapsed||!e.clipboardData)return;const r=e.clipboardData,l=t.getRangeAt(0),i=o(l.startContainer);i&&l.setStartBefore(i);const a=o(l.endContainer);a&&l.setEndAfter(a);const s=l.cloneContents();if(!s.querySelector(".katex-mathml"))return;const c=Array.prototype.map.call(s.childNodes,(e=>e instanceof Text?e.textContent:e.outerHTML)).join("");r.setData("text/html",c),r.setData("text/plain",n(s).textContent),e.preventDefault()})),e=e.default}()}));