使用URL解析URL字符串。
您可以获取pathname来提取MYTEXT，这将是由/分隔的最后一段。
您可以获取searchParams来检索特定查询参数的值，如period1=1664641287

const urlString = 'htts://query1.data.site.com/v7/finance/download/MYTEXT?period1=1664641287&period2=1696177287&interval=1d&events=history&includeAdjustedClose=true';

const url = new URL(urlString);

// You can get the last segment of the path like this 
console.log(url.pathname.split('/').slice(-1)[0]);

// You can also get query params like this if you need them
console.log(url.searchParams.get('period1'));

使用匹配最后一个/和?之间所有内容的正则表达式

const url = 'htts://query1.data.site.com/v7/finance/download/MYTEXT?period1=1664641287&period2=1696177287&interval=1d&events=history&includeAdjustedClose=true';
const regexp = /[^\/]+(?=\?)/;
match = url.match(regexp);
console.log(match);