Check if property exists using React.js

Question

I'm new to using react.js, and am trying to write a re-usable component that has an optional property passed to it. In the component, that optional property pulls data from a db using meteor, then I want to check if a property exists on the returned object (parent_task exists on task), and if exists, adds a link. This seems fairly simple, but I keep getting errors. Does anyone have any suggestions on what I might be missing? Is there a jsx gotcha that I'm missing?

<Header task={params.task_id} />  // rendering component with property  // Task List Header Header = React.createClass({   mixins: [ReactMeteorData],    getMeteorData() {     var handle = Meteor.subscribe('tasks');      return {       taskLoading: ! handle.ready(),       task: Tasks.findOne({_id: this.props.task})     }   },    getParentTaskLink() {     if (!this.data.taskLoading) {       var current_task = this.data.task;        if (parent_task in current_task) {  // or current_task.hasOwnProperty(parent_task)         console.log("parent_task exists!");       }     }   },    render() {     return (       <div className="bar bar-header bar-calm">         {this.getParentTaskLink()} // eventually return anchor element here         <h1 className="title">Hello World</h1>       </div>     )   } }); 

Answer 1

what is the prop in question? how about

{this.props.propInQuestion ? <a href="#">link</a> : null}