azure-devops-ui/Utilities/Dispatch.js

React components for building web UI in Azure DevOps

export class EventDispatch {
    constructor() {
        this.listeners = {};
    }
    addEventListener(eventType, callback) {
        if (!(eventType in this.listeners)) {
            this.listeners[eventType] = [];
        }
        this.listeners[eventType].push(callback);
    }
    dispatchEvent(event, data, type) {
        const delegates = this.listeners[type || event.type];
        if (delegates) {
            const stack = delegates.slice();
            for (let i = 0, l = stack.length; i < l; i++) {
                stack[i].call(this, event, data);
            }
        }
    }
    removeEventListener(eventType, callback) {
        if (!(eventType in this.listeners)) {
            return;
        }
        const stack = this.listeners[eventType];
        for (let i = 0, l = stack.length; i < l; i++) {
            if (stack[i] === callback) {
                stack.splice(i, 1);
                return;
            }
        }
    }
}