How to sum of text box value in form

Hi, Could you please any one solve my problem,
I want to sum of text box a and b that result display on textbox sum…

{name:“a”, view:“text”, value:10},
{name:“b”, view:“text”,value:5},
{name:“sum”, view:“text”, readonly:true, value:a+b}

You can use onChange events of the inputs to trigger a result recalculation

http://webix.com/snippet/d16226a8