how to pass values into array in javascript

I get values from php. In label values are like: a,b,c,d and in amount = 10,20,30,40

var label= <?php echo json_encode($label ); ?>;

var amount= <?php echo json_encode($Amount ); ?>;

Now I want to combine these values like { x: "label", y: amount } in javascript how I can do this ?