javascript array of objects access properties

// The user object will be the test data for the notes taken below,<br /> // ALL NOTE ARE AND INFO CAN BE FOUND AT HACKERNOON!<br /> // THIS IS NOT MY WORK, I AM ONLY POSTING IT TO GREPPER FOR EASE OF USE OF FINDING THIS<br /> // MATERIAL LATER IF NEED BE!<br /> // With that said enjoy the notes :D</p> <p>const user = {<br /> id: 101,<br /> email: ‘jack@dev.com’,<br /> personalInfo: {<br /> name: ‘Jack’,<br /> address: {<br /> line1: ‘westwish st’,<br /> line2: ‘washmasher’,<br /> city: ‘wallas’,<br /> state: ‘WX’<br /> }<br /> }<br /> }</p> <p>// To access the name of our user we will write:<br /> const name = user.personalInfo.name;<br /> const userCity = user.personalInfo.address.city;</p> <p>// This is the easy and straight-forward approach</p> <p>// But for some reason, if our user’s personal info is not available, the object structure<br /> // will be like this:<br /> const user = {<br /> id: 101,<br /> email: ‘jack@dev.com’<br /> }</p> <p>// Now if you try to access the name, you will be thrown “Cannot read property ‘name’<br /> // of undefined”<br /> const name = user.personalInfo.name; // Cannot read property ‘name’ of undefined</p> <p>//This is because we are trying to access the name key from an object that does not exist</p> <p>// The usual way how most devs deal with this scenario is<br /> const name = user && user.personalInfo ? user.personalInfo.name : null;<br /> // Undefined error will NOT be thrown as we check for existence before access</p> <p>// This is okay if your nested structure is simple, but if you have your data nested<br /> // 5 or 6 levels deep, then your code will look really messy like this:</p> <p>let city;<br /> if (<br /> data && data.user && data.user.personalInfo &&<br /> data.user.personalInfo.addressDetails &&<br /> data.user.personalInfo.addressDetails.primaryAddress<br /> ) {<br /> city = data.user.personalInfo.addressDetails.primaryAddress;<br /> }</p> <p>// for more information please visit:<br /> // https://hackernoon.com/accessing-nested-objects-in-javascript-f02f1bd6387f