You need to update the href attribute as

$('#down').attr('href', "@Url.Action("InvestigatorDetailsDownload", "ClinicalRegistryManager")?investigatorId=" + id);

Also note, when using .data() jQuery uses internal cache to store arbitrary data associated with element. If you want to update DOM the use .attr()

You need to update the href attribute as

$('#down').attr('href', "@Url.Action("InvestigatorDetailsDownload", "ClinicalRegistryManager")?investigatorId=" + id);

Also note, when using .data() jQuery uses internal cache. The statement data(key) will read default value only from data-key attribute afterwards it will use internal cache. the statement .data( key, value ) will store data in internal cache it will not update DOM.

You need to change the attribute as

$('#down').attr('href', "@Url.Action("InvestigatorDetailsDownload", "ClinicalRegistryManager")?investigatorId=" + id);

Also note, when using .data() jQuery uses internal cache to store arbitrary data associated with element. If you want to update DOM the use .attr()

You need to update the href attribute as

$('#down').attr('href', "@Url.Action("InvestigatorDetailsDownload", "ClinicalRegistryManager")?investigatorId=" + id);

Also note, when using .data() jQuery uses internal cache to store arbitrary data associated with element. If you want to update DOM the use .attr()