如何用js给input赋值

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

document.getElementById('myInput').value = '新的值';

<input type="text" class="myInputClass">

document.querySelector('.myInputClass').value = '新的值';

<input type="text" id="myInput">
<button id="myButton">点击赋值</button>

document.getElementById('myButton').addEventListener('click', function() {
    document.getElementById('myInput').value = '点击按钮后的新值';
});

<input type="text" value="初始值" id="myInput">
<script>
    document.getElementById('myInput').value = '脚本执行后的新值';
</script>

window.onload = function() {
    document.getElementById('myInput').value = '页面加载完成后的新值';
};