An improved solution for avoiding repetitive typeof checks when accessing nested properties in the DOM

Question

An improved solution for avoiding repetitive typeof checks when accessing nested properties in the DOM

One common issue I encounter when working with nested DOM objects is the risk of undefined errors. To address this, I often use a conditional check like the one shown below:

if("undefined" != typeof parent 
    && "undefined" != typeof parent.main 
    && "undefined" != typeof parent.main.location){
// Perform actions on an iframe page based on its parent location
}

Without such checks, there's a high chance of encountering undefined errors with deeply nested DOM objects. Is there a more efficient way to handle these situations without compromising stability?

javascript dom undefined

Answer 1

Answer №1

Being overly specific with checks is unnecessary in this situation.

Simply use the following code:

if(parent && parent.main && parent.main.location) {

Your original code would fail if trying to access a property on a null value. This approach handles that scenario more efficiently.

You may choose to make the last check more detailed, but the preceding checks only need to verify if the object exists.

Additionally, creating a function to streamline this process is an option worth considering.

function getNested(obj) {
    for (var i = 1; obj && i < arguments.length; ++i) {
        obj = obj[arguments[i]]
    }
    return obj;
}

getNested(parent, "main", "location");

Another approach you can take is:

if(((parent || {}).main || {}).location) {

In case of a falsey value being returned, the || {} will provide a substitute object to prevent errors.

Answer 2

Being overly specific with checks is unnecessary in this situation.

Simply use the following code:

if(parent && parent.main && parent.main.location) {

Your original code would fail if trying to access a property on a null value. This approach handles that scenario more efficiently.

You may choose to make the last check more detailed, but the preceding checks only need to verify if the object exists.

Additionally, creating a function to streamline this process is an option worth considering.

function getNested(obj) {
    for (var i = 1; obj && i < arguments.length; ++i) {
        obj = obj[arguments[i]]
    }
    return obj;
}

getNested(parent, "main", "location");

Another approach you can take is:

if(((parent || {}).main || {}).location) {

In case of a falsey value being returned, the || {} will provide a substitute object to prevent errors.

An improved solution for avoiding repetitive typeof checks when accessing nested properties in the DOM

Answer №1

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