SOURCE

function generate()
{
    var deeplink1=document.getElementById("deeplink1");
    var deeplink2=document.getElementById("deeplink2");
    var deeplinkUrl = new URL(deeplink1.value);
    var searchParams = new URLSearchParams(deeplinkUrl.search);
    var bc_fl_src=searchParams.get("bc_fl_src");

    var deeplink2Url = new URL(deeplink2.value);
    var searchParams2 = new URLSearchParams(deeplink2Url.search);
    searchParams2.set("bc_fl_src", bc_fl_src);
    deeplink2Url.search = searchParams2.toString();


    var deeplink3=document.getElementById("deeplink3");
    var ulink=document.getElementById("ulink");
    deeplink3.value = deeplink2Url.toString();
    ulink.value = "https://f1ytjb.cn/ulk/litetao?smburl="+ encodeURIComponent(deeplink2Url.toString());
}

<h3>淘特ios投放链接生成器</h3>
链接库获取的 deeplink:
</br>
<textarea id="deeplink1" cols="100" rows="8"></textarea>
<br/>
选品的 deeplink：
</br>
<textarea id="deeplink2" cols="100" rows="8"></textarea>
<br/><br/>
<input type="button" value="生成ios投放地址" onclick="generate()"/>

<br/><br/>
deeplink
</br>
<textarea id="deeplink3" cols="100" rows="6"></textarea>
<br/><br/>
ulink
</br>
<textarea id="ulink" cols="100" rows="6"></textarea>