put message in whatsapp api href code example
Example: whats app link target blank
<button onclick="javascript:{window.open('https://api.whatsapp.com/send?phone=55myphonehere&text='+encodeURIComponent('My text here'),'_blank')}" ></button>
<button onclick="javascript:{window.open('https://api.whatsapp.com/send?phone=55myphonehere&text='+encodeURIComponent('My text here'),'_blank')}" ></button>