SOURCE

const eventBus = {
    array: {

    },
    on: function (type, fn) {
        this.array[type] = this.array[type] || []
        this.array[type].push(fn)
    },
    off: function (type, fn) {
        const fns = this.array[type]
        if (!fns) return
        const index = this.array[type].findIndex((item) => item === fn)
        if (index > -1) {
            this.array[type].splice(index, 1)
        }
    },
    emit: function (type, data) {
        const fns = this.array[type]
        if (!fns) return
        fns.forEach(fn => {
            fn(data)
        })
    }
}

const fn = (data) => console.log('click', data)

eventBus.on('click', fn)

eventBus.emit('click', '22')
eventBus.emit('click', '33')


eventBus.off('click', fn)
eventBus.emit('click', '55')