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DOM Form Events In Javascript

 <!DOCTYPE html>

<html>
    <head>
        <title>Form Events</title>
    </head>
    <body>
        <h1>Form Events</h1>
        <form action="" onsubmit="submitFunction()">
            <label>First Name</label>
            <input type="text" placeholder="first_name" id="fname" value="adnan" onfocus="focusFunction(this)" onblur="blurFunction(this)" oninput="inputFunction(this)"
            onselect="selectFunction(this)" />
            <br>
            <br>
            <label>Last Name</label>
            <input type="text" placeholder="last_name" id="lname" onfocus="focusFunction(this)" onblur="blurFunction(this)"
            oninput="inputFunction(this)"
            oninvalid="alert('please fill the last name feild..!')"
            required
            />
            <br>
            <br>
            <label>Favourit Fruit</label>
            <select id="fruit" onfocus="focusFunction(this)" onblur="blurFunction(this)"
            onchange="changeFunction(this)"
            >
                <option value="0">Select...</option>
                <option value="1">Apple</option>
                <option value="2">Orange</option>
            </select>
            <br>
            <br>
            <button type="submit">Submit Event</button>
        </form>
        <div id="text" style="border:1px solid pink">

        </div>
        <script>
            function focusFunction(element){
                // document.getElementById('fname').style.background = 'lime';
                element.style.background = 'lime';
            }
            function blurFunction(element){
                // document.getElementById('fname').style.background = 'lime';
                element.style.background = '';
            }

            // Input event.
            // this event only work on input and textarea
            // this event trigger when we start writing on the input or textarea
            function inputFunction(element){
             var val = element.value;
             document.querySelector('#text').innerHTML = val;
            }

            // onchange event
            // this event work like oninput event but run on if chnage happen than previous state.
            // see the chnage effect on chnage select option.
            // input feld pr onchnage event teb kaam krega jb ap lost focus kreinge mean on feild se focus remove kreinge.

            function changeFunction(element){
                var val = element.value;
                document.querySelector('#text').innerHTML = val;
            }

            // onselect event
            // this event run when we select content in input feild
            // we use this event in input or textarea.
            function selectFunction(element){
                var val = element.value;
                console.log(val);
                console.log('you have selected some text');
            }

            // onsubmit event
            // this event we use on submit button/ input
            // when user fill the form and submit the form, this event triggers.
            function submitFunction(){
                var x = document.getElementById('fname').value;
                alert('Hello '+ x);
            }

            // oninvalid event
            // when user submit form with empty input feild if feild is required than invalid event fire(run).
        </script>
    </body>
</html>

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