@saltcorn/puppeteer-v17
Version:
A high-level API to control headless Chrome over the DevTools Protocol
54 lines (53 loc) • 1.92 kB
JavaScript
/**
* Mitt: Tiny (~200b) functional event emitter / pubsub.
* @name mitt
* @returns {Mitt}
*/
export default function mitt(all) {
all = all || new Map();
return {
/**
* A Map of event names to registered handler functions.
*/
all: all,
/**
* Register an event handler for the given type.
* @param {string|symbol} type Type of event to listen for, or `"*"` for all events
* @param {Function} handler Function to call in response to given event
* @memberOf mitt
*/
on: function (type, handler) {
var handlers = all.get(type);
var added = handlers && handlers.push(handler);
if (!added) {
all.set(type, [handler]);
}
},
/**
* Remove an event handler for the given type.
* @param {string|symbol} type Type of event to unregister `handler` from, or `"*"`
* @param {Function} handler Handler function to remove
* @memberOf mitt
*/
off: function (type, handler) {
var handlers = all.get(type);
if (handlers) {
handlers.splice(handlers.indexOf(handler) >>> 0, 1);
}
},
/**
* Invoke all handlers for the given type.
* If present, `"*"` handlers are invoked after type-matched handlers.
*
* Note: Manually firing "*" handlers is not supported.
*
* @param {string|symbol} type The event type to invoke
* @param {Any} [evt] Any value (object is recommended and powerful), passed to each handler
* @memberOf mitt
*/
emit: function (type, evt) {
(all.get(type) || []).slice().map(function (handler) { handler(evt); });
(all.get('*') || []).slice().map(function (handler) { handler(type, evt); });
}
};
}