JavaScript, can you explain the significance of the "length" set in this function?

I found this code snippet online and used it in my function.

Surprisingly, it works perfectly.

However, I'm puzzled by the use of .length in the for loop statement.

Isn't length a measurement of how long something is?

It's somewhat like the word width, isn't it?

So, why are we measuring the length of a radio button to check if it exists? What kind of length is being referred to here?

function monte(fichier_c)
    {
    var boutonRadio = document.getElementsByName("id_ordre_transport");
    var monte = "rien";

    for (var i = 0; i < boutonRadio.length; i++)
        {
        if (boutonRadio[i].checked)
            {
            //alert(fichier_c);
            //alert(boutonRadio[i].value);
            //alert( "#monte"+boutonRadio[i].value);
            var monte = fichier_c+"#monte"+boutonRadio[i].value;
            }
        }
    if ( monte == "rien" )
        {
        //alert(fichier_c);
        var monte = fichier_c;
        }

        return monte;
        }

Could someone please provide clarity on the purpose of this 'length' parameter?

Answer №1

What is the purpose of using .length in the for loop statement?

The variable name boutonRadio may be misleading as it does not represent a single button.

Doesn't "Length" refer to something that can be measured in terms of size?

Yes, that's correct.

Then why are we measuring the length of a radio button to determine its existence?

It's not about the length of an individual radio button, rather about the collection of elements with the same name.

What kind of length are we talking about here?

The document.getElementsByName() method returns a collection of elements - it could be one, none, or many.

This collection, similar to an array, is iterated through the loop using indices from 0 to its .length. The individual radio buttons are accessed as boutonRadio[i] within the loop.

Answer №2

In JavaScript, the code

document.getElementsByName("id_ordre_transport");
retrieves all elements (or an array of elements) with the name "id_ordre_transport". On an HTML page, this could include multiple radio buttons. The code boutonRadio.length indicates the number of radio buttons with the name "id_ordre_transport".

for (var i = 0; i < boutonRadio.length; i++)
    {
    if (boutonRadio[i].checked)
        {
        //alert(fichier_c);
        //alert(boutonRadio[i].value);
        //alert( "#monte"+boutonRadio[i].value);
        var monte = fichier_c+"#monte"+boutonRadio[i].value;
        }
 }

The above code iterates through all elements and checks whether a radio button is checked or unchecked by using boutonRadio[i].checked. If it is checked, then it assigns a value to the variable monte.

An insightful comment provided above: "Length is a property of an array. It measures the array's length. For example, var a=[1,2,3] means array 'a' has a length of 3." -Mukund Kumar 18 hours ago

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