CODEWITHSUNDEEP
javascriptarraysundefined
Светослав Илиев
Светослав Илиев

Reputation: 35

Array[element+1] returns undefined?

I'm trying to check whether a given element in an array is bigger than it's two adjacent elements, but array[element+1] returns - undefined. However when I try with array1[(element-1)+2] it works just fine.

This is the array:

var array1 = [1, 5, 56, 6, 7, 8, 12, 5, 1];

And my Code:

function biggestOfThree(element){
    if((element == 0)||(element == array1Length-1)){
        document.write("There aren't 2 adjacent elements in the array");
    }
    else{
        if((array1[element]>array1[element+1])&&(array1[element]>array1[element-1])){
            document.write(array1[element] + " is bigger than it's adjacent elements")
        }
        else{
            document.write(array1[element] + " isn't bigger than it's adjacent elements")
        }
    }

}

...and the function for receiving the element by the user:

function assign(){
var i_element = document.getElementById('indexOfTheElement');
var i = i_element.value;
    biggestOfThree(i)
}

Upvotes: 2

Views: 112

Answers (1)

Anirudh Ramanathan
Anirudh Ramanathan

Reputation: 46778

The error you see is due to JavaScript's dynamic typing. Use parseInt

var i = parseInt(i_element.value);

The + 1 still regards it a string and appends 1 to it. Performing a -1 forces it to consider it an int. Hence your results. Always convert to int using parseInt()

"1" + 1 = 11
"1" - 1 = 0

As @Elias said, it is best to define the radix when using parseInt.

parseInt(string, 10)
                  ^ radix

Upvotes: 6

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