string and button question

Hi,

i added a textbox and a button to my html file.
the user is insert a string to the textbox.

i want that when click on the button. the function take the string and for example use it for <a href = " www.THE STRING.com "> button </a>

so i need put also variable

how can i do it in JS???
thanks a lot

document.location.href=document.getElementById('textbox1').value;