var inputs = document.getElementsByTagName("input");
    
for (var i = 0; i < inputs.length; i++)
{
    if (document.getElementById("value_[0-9]"))
    {
        alert('found: ' + inputs[i].value);
    }
    else
    {
        alert(inputs[i].value);
    }
}

I'm using the condition to get only input IDs that starts with value_

if (document.getElementById("value_[0-9]"))

but nothing is true where I have 5 or more IDs in my form. i.e. value_1, value_2, value_3 etc..

var inputs = document.getElementsByTagName("input");
    
for (var i = 0; i < inputs.length; i++)
{
    if (document.getElementById("value_[0-9]"))
    {
        alert('found: ' + inputs[i].value);
    }
    else
    {
        alert(inputs[i].value);
    }
}

I'm using the condition to get only input IDs that starts with value_

if (document.getElementById("value_[0-9]"))

but nothing is true where I have 5 or more IDs in my form. i.e. value_1, value_2, value_3 etc..

• javascript
• dom-events

3 Answers 3

You use wrong method for that. Simply check the id property of a certain element in the list:

for (var i = 0, len = inputs.length; i < len; i++) {
    if (inputs[i].id.indexOf("value_") === 0) {
        // alert("Found: " + inputs[i].value);
    }
}

Combine document.querySelectorAll with Array.prototype.slice to make it an Array

Array.prototype.slice.call(document.querySelectorAll('input[id^="value_"]'));

From here you can do your favorite loop, e.g. Array.prototype.forEach

[].map.call(document.getElementsByTagName( 'input' ), function( input ) {
    return input.id.indexOf( 'value_' ) === 0;
}).forEach(function( input ) {
    // do whatever here
});