test-whiteboard/libs/eventEmitter.js

https://gitlab.gridsum.com/gov_law_tech/FrontEnd/whiteboard

export  default class  EventEmitter{
    constructor(){
        this.callbacks={

        };
    }
    on (key,callback) {
        if(!this.callbacks)
        {
            this.callbacks={};
        }
        if(!this.callbacks[key])
        {
            this.callbacks[key] = [];
        }
        this.callbacks[key].push(callback);
    }
    emit (key,...args) {
        if(!this.callbacks)
        {
            this.callbacks={};
        }
        var events = this.callbacks[key];
        if(!events)
        {
            return;
        }
        for(var i=0;i<events.length;i++)
        {
            events[i].apply(this,args);
        }
    }
}