You can try below
<lightning:button variant="brand" label="Charge" data-value="{!s.Id}" onclick="{!c.callMyCallback}" />
callMyCallback : function(cmp, event, helper) {
var value = event.target.dataset.value;
}
You can try below
<lightning:button variant="brand" label="Charge" data-value="{!s.Id}" onclick="{!c.callMyCallback}" />
callMyCallback : function(cmp, event, helper) {
var value = event.target.dataset.value;
}