set a value to a global array within a function

Question

set a value to a global array within a function

After writing the following javascript code:

<script language="javascript" type="text/javascript">
    var name = new Array();
    var i = 0;
    function doSomething() {
        name[i] = "a";
        alert(name[i]);
        i++;
    }        
</script>

I encountered an issue where it alerted undefined instead of a in my Chrome browser. To troubleshoot, I tested alert(i) and that worked properly.

Is there a way to properly assign values to a global array within a function?

Update: The problem was resolved by simply renaming the array, which fixed the issue. But what caused this solution to work?

javascript arrays

Answer 1

Answer №1

name is a property that belongs to the window object:

This property can be used to get or set the name of the window.

Keep in mind that global variables are actually properties of the global object (window). Interestingly, Firefox allows you to override this property, while Chrome does not. Test it out in the Chrome console:

> name = [];
[]
> typeof name
"string"

The expected output should be "object".

Lesson learned: Avoid using a global variable named name. Instead, consider renaming your variable for better results. Check out this example for reference.

Answer 2

name is a property that belongs to the window object:

This property can be used to get or set the name of the window.

Keep in mind that global variables are actually properties of the global object (window). Interestingly, Firefox allows you to override this property, while Chrome does not. Test it out in the Chrome console:

> name = [];
[]
> typeof name
"string"

The expected output should be "object".

Lesson learned: Avoid using a global variable named name. Instead, consider renaming your variable for better results. Check out this example for reference.

Answer 3

Answer №2

You are signaling name[i] outside of the function; however, i has already been incremented within the function.

thus alert(name[0]);

http://jsfiddle.net/7J2nP/4/

Answer 4

You are signaling name[i] outside of the function; however, i has already been incremented within the function.

thus alert(name[0]);

http://jsfiddle.net/7J2nP/4/

Answer 5

Answer №3

One possible explanation for this issue could be due to hoisting.
It's a common misconception that variables and functions are defined in the same order as they appear in your script, but in reality, when the javascript interpreter parses your script, it moves all the variables to the top of the scope. This also applies to function declarations. It's likely that in your case, the function declaration has been hoisted above the variables, causing them not to be available within its scope. This behavior may vary depending on the browser used. One way to fix this is by using a function expression instead.

var name = new Array();
var i = 0;
var doSomething = function() {
    name[i] = "a";
    alert(name[i]);
    i++;
}

doSomething(); // alerts 'a'

UPDATE

I just tested this solution in Chrome and unfortunately, it did not work as expected. Felix's answer seems to be a better alternative.

Answer 6

One possible explanation for this issue could be due to hoisting.
It's a common misconception that variables and functions are defined in the same order as they appear in your script, but in reality, when the javascript interpreter parses your script, it moves all the variables to the top of the scope. This also applies to function declarations. It's likely that in your case, the function declaration has been hoisted above the variables, causing them not to be available within its scope. This behavior may vary depending on the browser used. One way to fix this is by using a function expression instead.

var name = new Array();
var i = 0;
var doSomething = function() {
    name[i] = "a";
    alert(name[i]);
    i++;
}

doSomething(); // alerts 'a'

UPDATE

I just tested this solution in Chrome and unfortunately, it did not work as expected. Felix's answer seems to be a better alternative.

set a value to a global array within a function

Answer №1

Answer №2

Answer №3

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