try catch in javascript for undefined check

Question

I have a method findResult

function findResult(response){
 if (response[0].firstProperty.Value > 0)
     return true;
 else false;
}

In this method, if response object is undefined we get a javascript error. My question is whether to use explicit undefined checks or wrap the code around try/catch as shown below:

function findResult(response){
 try{
    if (response[0].firstProperty.Value > 0)
     return true;
    else return false;
 }
 catch(e){
   return false;
 }

}

there's a myriad of ways to handle this, and not a single one of them has specifically heavy impact compared to the others. (if vs try()catch(){} does not matter) stackoverflow.com/questions/19727905/… The real question here is whether you want to continue executing code in the same block if response is null. if the answer is no, it really does not matter which solution you choose — Timothy Groote
– Timothy Groote, Commented Jan 4, 2018 at 8:11
Thanks Timothy. With explict check, the condition check becomes too long Ex: if (response && response.length && response[0].firstProperty.Value > 0) — Sandeep Nagaraj
– Sandeep Nagaraj, Commented Jan 4, 2018 at 8:57
So was checking what is the optimal approach. Thanks for the repsonse — Sandeep Nagaraj
– Sandeep Nagaraj, Commented Jan 4, 2018 at 8:58

klugjo · Accepted Answer · 2018-01-04 08:09:37Z

0

You can avoid the try catch with a simple check

if (response && response.length && response[0].firstProperty.Value > 0) { ... }

If you have access to lodash:

if (_.get(response, '[0].firstProperty.Value', 0) > 0) { ... }

answered Jan 4, 2018 at 8:09

klugjo

21k10 gold badges65 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Renan Araújo · Accepted Answer · 2018-01-04 10:24:50Z

Javascript doesn't have this feature native.

But there are some implementations of this on the web. For example:

function deepGet (obj, props, defaultValue) {
    // If we have reached an undefined/null property
    // then stop executing and return the default value.
    // If no default was provided it will be undefined.
    if (obj === undefined || obj === null) {
        return defaultValue;
    }

    // If the path array has no more elements, we've reached
    // the intended property and return its value
    if (props.length === 0) {
        return obj;
    }

    // Prepare our found property and path array for recursion
    var foundSoFar = obj[props[0]];
    var remainingProps = props.slice(1);

    return deepGet(foundSoFar, remainingProps, defaultValue);
}

Usage:

var rels = {
    Viola: {
        Orsino: {
            Olivia: {
                Cesario: null
            }
        }
    }
};
var oliviaRel = deepGet(rels, ["Viola", "Orsino", "Olivia"], {});

Source: http://adripofjavascript.com/blog/drips/making-deep-property-access-safe-in-javascript.html

Collectives™ on Stack Overflow

try catch in javascript for undefined check

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related