js获取表单里面input的值

// HTML
<input type="text" id="myInput">

// JavaScript
var inputValue = document.getElementById('myInput').value;
console.log(inputValue);

// HTML
<input type="text" name="myInput">

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

// HTML
<input type="text" class="myInput">

// JavaScript
var inputValue = document.querySelector('.myInput').value;
console.log(inputValue);

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