How to add onChange function for all HTML form fie

Question

My HTML Page has 10 Text Fields.

Currently no onChange EVENT is available for all ten fields.

<input type="text" name="text1" value="1">
<input type="text" name="text2" value="2">
<input type="text" name="text3" value="3">
<input type="text" name="text4" value="">
<input type="text" name="text5" value="">
<input type="text" name="text6" value="">...

Now, I want to add onChange Function in all fields whose field is of input type.

How do I add onChange or onBlur even in my JS section?

In onChange function, I will call ajax function which will validate whether the field has Hacking Keywords.

So my question is:

How do I add onChange function for all form fields. My field should dynamically be like below:

<input type="text" name="text1" value="1" onChange="javascript:fnName" onBlur="javascript:fnName" >
<input type="text" name="text2" value="2" onChange="javascript:fnName" onBlur="javascript:fnName" >
<input type="text" name="text3" value="3" onChange="javascript:fnName" onBlur="javascript:fnName" >
<input type="text" name="text4" value="" onChange="javascript:fnName" onBlur="javascript:fnName" >
<input type="text" name="text5" value="" onChange="javascript:fnName" onBlur="javascript:fnName" >
<input type="text" name="text6" value="" onChange="javascript:fnName" onBlur="javascript:fnName" >
<input type="text" name="text7" value="" onChange="javascript:fnName" onBlur="javascript:fnName" >

Answer 1

[].forEach.call(document.querySelectorAll("input"), function(input) {
  input.addEventListener("change", fnName, false);
  input.addEventListener("blur", fnName, false);
});

Answer 2

Try something like:

var inputList = document.getElementsByTagName("input");
for(var i=0;i<inputList.length;i++){
    inputList[i].onchange = function(){
        //function here
    }
    inputList[i].onblur = function(){
        //function here
    }
}

Answer 3

getElementsByTagname() gets you an array of all input. Interate over them and addEventListener.

Or use jQuery's $('input').on('change'...)

Answer 4

you can try to give change function to your form using

$('.form :input').change(function(e){
   $('#log').prepend('<p>Form changed ' + $(e.target).attr('id') + '</p>')
});

Demo1

Demo2

Answer 5

This can be achieved with vanilla JavaScript as zvona suggests.

Here is a simple loop to mock an HTML5 placeholder. <<DEMO>>

var prompt = 'Type something here';

var textFields = document.querySelectorAll('input[name^="text"]');
var index = 0;

for (index = 0; index < textFields.length; ++index) {
    var textField = textFields[index];
    textField.addEventListener('change', onChangeHandler);
    textField.addEventListener('focus', onFocusHandler);
    textField.addEventListener('blur', onBlurHandler);
    textField.value = prompt;
    console.log(textField);
}

function onChangeHandler() {
    // Do something...
}

function onFocusHandler() {
    if (this.value === prompt) {
        this.value = '';
    }
}

function onBlurHandler() {
    if (this.value === '') {
        this.value = prompt;
    }
}