when you will try to assign integer value to nvarchar attribute in MS CRM like below

var IntVal=10;

Let’s say we have one field named “ABC” having nvarchar datatype

crmForm.all.ABC.DataValue=IntVal;

you will get error “This control only accepts strings or null as input”. to solve this issue you can use toString() method of JS like below

crmForm.all.ABC.DataValue=IntVal.toString();

Enjoy !!!