js获取页面input的值

<input type="text" id="myInput">
<button onclick="getValue()">获取值</button>

<script>
function getValue() {
    var inputValue = document.getElementById('myInput').value;
    console.log(inputValue);
}
</script>

<input type="text" name="myInput">
<button onclick="getValue()">获取值</button>

<script>
function getValue() {
    var inputs = document.getElementsByName('myInput');
    for (var i = 0; i < inputs.length; i++) {
        console.log(inputs[i].value);
    }
}
</script>

<input type="text" class="myInput">
<button onclick="getValue()">获取值</button>

<script>
function getValue() {
    var inputValue = document.querySelector('.myInput').value;
    console.log(inputValue);
}
</script>

<form id="myForm">
    <input type="text" name="username">
    <input type="password" name="password">
    <button type="submit">提交</button>
</form>

<script>
document.getElementById('myForm').addEventListener('submit', function(event) {
    event.preventDefault(); // 阻止表单默认提交行为
    var formData = new FormData(this);
    for (var pair of formData.entries()) {
        console.log(pair[0]+ ', '+ pair[1]); 
    }
});
</script>