Passing an array as parameter in JavaScript

Question

I have an array, and I want to pass it as a parameter in a function such as:

function something(arrayP){
    for(var i = 0; i < arrayP.length; i++){
          alert(arrayP[i].value);
    }
 }

I'm getting that arrayP[0] is undefined, which might be true as inside the function I never wrote what kind of array arrayP is. So,

Is is possible to pass arrays as parameters?
If so, which are the requirements inside the function?

I suggest you learn more about arrays: https://developer.mozilla.org/en/JavaScript/Guide/Predefined_Core_Objects#Array_Object — Felix Kling, Dec 18 '10 at 19:48

score 37 · Answer 1 · answered Dec 18 '10 at 19:07

37

Just remove the .value, like this:

function(arrayP){    
   for(var i = 0; i < arrayP.length; i++){
      alert(arrayP[i]);    //no .value here
   }
}

Sure you can pass an array, but to get the element at that position, use only arrayName[index], the .value would be getting the value property off an object at that position in the array - which for things like strings, numbers, etc doesn't exist. For example, "myString".value would also be undefined.

answered Dec 18 '10 at 19:07

Nick Craver

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`String.prototype.value = "Hi Nick I broke your example!"` /evil codez don't use – Ivo Wetzel Dec 18 '10 at 19:46
1

@IvoWetzel Why do you considered it as evil code? Is the code that he provided vulnerable? – 5ervant - techintel.github.io Sep 02 '15 at 15:18

score 5 · Answer 2 · answered Dec 18 '10 at 19:09

5

JavaScript is a dynamically typed language. This means that you never need to declare the type of a function argument (or any other variable). So, your code will work as long as arrayP is an array and contains elements with a value property.

answered Dec 18 '10 at 19:09

Amnon

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score 2 · Answer 3 · answered Dec 18 '10 at 19:07

2

It is possible to pass arrays to functions, and there are no special requirements for dealing with them. Are you sure that the array you are passing to to your function actually has an element at [0]?

answered Dec 18 '10 at 19:07

ClosureCowboy

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Passing an array as parameter in JavaScript

3 Answers3

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