JS 過濾HTML標簽，取得純文本

一、過濾掉所有HTML標簽如下：

str.innerHTML.replace(/<.*?>/g,"")

二、過濾掉帶屬性的某一個標簽，如<span class='aa'></span>標簽：

var str = "<p>這里是測試過濾<span class='aa'>span標簽的哦</span></p>";
str.replace(/<span (.*?)>/gi,"");

str.replace(/<\/span>/gi,"");

三、過濾掉不帶屬性的某一個標簽，如<span></span>標簽：

var str = "<p>這里是測試過濾<span>span標簽的哦</span></p>";
str = str.replace(/<span>/gi,"");
str = str.replace(/<\/span>/gi,"");

var str = "<p>這里是測試過濾<span>span標簽的哦</span></p>";
str.replace(/<span>/gi,"").replace(/<\/span>/gi,"");

四、過濾配對<span></span>標簽（不包含屬性），一起過濾掉

var str = "<p>這里是測試過濾<span>span標簽的哦</span></p>";
str.replace(/<span>|<\/span>/gi,"");

五、過濾配對<span ></span>標簽（包含屬性），一起過濾掉

var str = "<p>這里是測試過濾<span>span標簽的哦</span></p>";
str.replace(/<span\s*[^>]*>(.*?)<\/span>/ig,"$1");

var str = "<p>這里是測試過濾<span>span標簽的哦</span></p>";
str.replace(/<span.*?>|<\/span>/ig,"");

注意事項：

var str = "<p>這里是測試過濾<span>span標簽的哦</span></p>";
str.replace(/<span>/gi,"");
str.replace(/<\/span>/gi,"");

結果如下：

從結果中可以看出<span>並沒有過濾掉，原因是原字符串不會改變

執行完第一句replace后，可以看到第二句str仍為原始值

參考：

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace