我用Material Design组件制作了一个表单。
当自动填充填充输入时，我的TextField浮动标签会浮动，但在用户输入时不会浮动。
function fillFields() {
$("#passwordTextField").val("test");
$("#usernameTextField").val("test");
}p.highlight-red-on-error {
transition: color 180ms cubic-bezier(0.4, 0, 0.2, 1);
}
div.mdc-text-field--invalid~p.highlight-red-on-error {
color: #b00020;
}<head>
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha256-3edrmyuQ0w65f8gfBsqowzjJe2iM6n0nKciPUp8y+7E=" crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
<link href="https://fonts.googleapis.com/css?family=Work+Sans" rel="stylesheet">
<link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">
<link rel="stylesheet" href="https://unpkg.com/material-components-web@latest/dist/material-components-web.min.css">
<script src="https://unpkg.com/material-components-web@latest/dist/material-components-web.min.js"></script>
</head>
<body>
<div>
<div class="mdc-text-field">
<input type="text" id="usernameTextField" name="username" class="mdc-text-field__input" pattern="[A-Za-z]*" required minlength=3 maxlength=32 data-mdc-auto-init="MDCTextField">
<label for="usernameTextField" class="mdc-floating-label">Username</label>
<div class="mdc-line-ripple"></div>
</div>
<p class="highlight-red-on-error">Username must be between 3 and 32 characters and contain only alphanumeric characters.</p>
</div>
<br>
<!-- password field -->
<div>
<div class="mdc-text-field" data-mdc-auto-init="MDCTextField">
<input type="password" id="passwordTextField" name="password" class="mdc-text-field__input" pattern="[A-Za-z!%^&*$?~`=+-_()]*" required minlength=8>
<label for="passwordTextField" class="mdc-floating-label">Password</label>
<div class="mdc-line-ripple"></div>
</div>
<p class="highlight-red-on-error">Password must be at least 6 characters. Some special charcaters are not allowed</p>
</div>
<p>
Typing in the fields doesn't float the labels, but using autofill does.
</p>
<button onClick="fillFields()">Fill fields (doesn't float labels)</button>
<script>
window.mdc.autoInit();
// from https://github.com/material-components/material-components-web/tree/master/packages/mdc-auto-init#using-as-part-of-material-components-web
</script>
</body>如您所见，既不通过JavaScript编辑字段，也不键入它们会浮动标签。仅使用自动填充功能。此外，autoInit();似乎不起作用。
我发现使用autoInit();由于某种原因不起作用，所以我不得不手动初始化组件。
TextFields的一个例子（使用jQuery）是：
$('.mdc-text-field').each(function (i, obj) {
mdc.textField.MDCTextField.attachTo(obj);
});
上面的代码为类mdc-text-field的所有项应用了正确的属性和方法等