getElementsByName won't loop through entire array

Question

The following code executes on the press of a button. It works fine alerting one string of the getElementsByName array, but when introduced to a loop, it still only alerts the first string value, and nothing more:

function checkvals() {

var input = document.getElementsByName('ModuleTitle', 'ModuleCode', 'BuildingName', 'Day');
var i = 0;

for (i = 0; i <= input.length; i++){
alert(input[i].value);
}
}

user1106925 · Accepted Answer · 2012-02-25 23:55:34Z

3

That's because getElementsByName only accepts one argument, so it's only fetching the first name.

You can build a full collection like this...

var names = ['ModuleTitle', 'ModuleCode', 'BuildingName', 'Day'];

var input = [];
for(var i = 0; i < names.length; i++) {
    var name_els = document.getElementsByName(names[i]);
    for(var j = 0; j < name_els.length; j++) {
        input.push(name_els[j]);
    }
}

Then loop over the input Array, (or just do your work in the inner loop).

Additionally, you have a bug.

This...

for (i = 0; i <= input.length; i++){

should be this...

for (i = 0; i < input.length; i++){

...otherwise, you'll go one past the last index.

answered Feb 25, 2012 at 23:55

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user1106925

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Comments

ruakh · Accepted Answer · 2012-02-25 23:55:17Z

0

That's because getElementsByName only takes a single name argument, and returns all elements with that value for their name attribute. (See https://developer.mozilla.org/en/DOM/document.getElementsByName.) If you have multiple names to look up, you'll have to call it multiple times.

answered Feb 25, 2012 at 23:55

ruakh

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1 Comment

user1228907 Over a year ago

But it still only alerts one value even when I do this: function checkvals() { var input = document.getElementsByName('ModuleTitle', 'ModuleCode', 'BuildingName', 'Day'); alert(input[0].value); alert(input[1].value); alert(input[2].value); alert(input[3].value); }

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