Question

I have an array of objects with the following format:

obj = { ref: 8, id: "obj-8" }

and a function which uses jQuery’s grep method to return an item from that array, by searching for the object ref property:

function returnObj(arr,r){
    return $.grep(arr, function(elem,index){ return elem.ref == r; })[0];
}

If I use this function on an array that has undefined elements in it (they were previously deleted using the delete operator), I get the following error: Uncaught TypeError: Cannot read property ‘ref’ of undefined, which I assume is thrown when an undefined element is encountered.

How can I modify the function so it doesn’t break?

Answer 1

Just check to see if the current item is undefined, or simply “falsey” if you expect specifc objects, and return false if so.

function returnObj(arr,r){
    return $.grep(arr, function(elem,index){ 
                           return elem ? elem.ref == r : false;
                       })[0];
}

---

Here’s another option. Since you’re using delete to remove the items, you can use the native .filter method, which skips over non-existent array members.

function returnObj(arr,r){
    return arr.filter(function(elem){ elem.ref == r})[0];
}