how to combine two vars in javascript?

Question

i am trying to create dynamic textboxes. The textbox should be created only if the previous textbox is non-empty. So far i have done this

<!DOCTYPE html> <html> <head> <script> var i=0; function myFunction() { var box = document.createElement("input"); box.type = "text"; var str=box+i; if(i==0) { document.body.appendChild(box); } else if(document.getElementById('str').value!=0) { document.body.appendChild(box); } i++; } </script> </head> <body> <input type="button" id="button" onclick="myFunction()" value="Show box" /> </body> </html>

but str is not recognised as element id. Any help will be appreciated.

What are you trying to do? There's no element on your page with ID str and you're not assigning IDs to any elements you create. Also, both branches of your if statement are doing the same thing. — Michael Mior
– Michael Mior, Commented Oct 8, 2013 at 16:00

GameAlchemist · Accepted Answer · 2013-10-08 18:07:45Z

var i = 0; function myFunction() { var lastInput = document.getElementById('box' + i); if (!lastInput) { // always put first input document.body.appendChild(createInput(0)); } else if (lastInput.value != 0) { // append another one only if previous input content is non-null i++; document.body.appendChild(createInput(i)); } } function createInput(i) { var box = document.createElement("input"); box.type = 'text'; box.id = 'box' + i; box.value = 0; return box; }

yeah, its working. Thank you. well,i managed to fix my code also.. :)
Ok, all the best ! so put my anwswer as accepted, and if your final solution is significatively different, edit your post to add the solution you came to. Cheers.

vp_arth · Accepted Answer · 2013-10-08 18:10:57Z

Your wrongs:

str = 'box' + i;
Forget to assign box.id = str
Use getElementById(str) instead of getElementById('str')

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