更改

str = document.getElementsByClassName('mw-parser-output')[0].outerText;

var reg = /(?:([0-9A-Za-z_])([\u4e00-\u9fa5]))|(?:([\u4e00-\u9fa5])([0-9A-Za-z_]))/g;

let s1 = /([0-9A-Za-z_])([\u4e00-\u9fa5])/g;

let s2 = /([\u4e00-\u9fa5])([0-9A-Za-z_])/g;

temp = str.replace(s1, "$1 $2");

   while( match = reg.exec(targetText) !== null ) {

str = temp.replace(s2, "$1 $2");

     this = this.replace(reg, "$1$3 $2$4");

});