Why Does My Function Return Undefined Even with an Explicit Return Statement?

Function Returning Undefined with Explicit Return Statement

In a scenario where a function is intended to check values in an array of objects but persistently returns undefined, it's crucial to examine the function's structure and the usage of the forEach method.

The problem arises when the return statement is placed within the callback function passed to forEach instead of the actual getByKey function. This means that the function itself always returns undefined, regardless of the return statement within the callback.

To resolve this issue, the function can be rewritten to use the return statement correctly:

function getByKey(key) {
    var found = null;
    data.forEach(function (val) {
        if (val.Key === key) {
            found = val;
        }
    });
    return found;
}

In this revised code, the return statement is placed within the getByKey function, ensuring that the function returns either the found object or null if the key is not found.

Alternatively, a simple for loop can be used for greater efficiency, as it would iterate over the array elements until the desired item is found:

function getByKey(key) {
    for (var i = 0; i < data.length; i++) {
        if (data[i].Key === key) {
            return data[i];
        }
    }
}

It's important to note that the revised code returns the object value corresponding to the key, rather than just the key itself. This provides greater flexibility in accessing the desired data.

The above is the detailed content of Why Does My Function Return Undefined Even with an Explicit Return Statement?. For more information, please follow other related articles on the PHP Chinese website!