cancel static method
Implementation
static String cancel() {
var script = "if (window.BootpayCancel && window.BootpayCancel.postMessage) { BootpayCancel.postMessage(JSON.stringify(data)); }";
// var script = "BootpayCancel.postMessage(JSON.stringify(data));";
return "if (data.event === 'cancel') { $script }";
}