jQuery警报返回代码

Question

我正在使用以下HTML和JavaScript来显示#username <input>元素的值:

<form action="#" method="post">
  Username: <input type="text" name="username" /><br />
  Password: <input type="password" name="password" /><br />
  <input class="test" type="submit" id="thing" value="Log In" />
</form>

$(document).ready(function() {
  $('input#thing').on('click', function() {
    var name = $('#username').val;
    alert(name);
  });
});?

当我在浏览器中运行它时,我会收到警报

function (value) {
    var hooks, ret, isFunction, elem = this[0];
    if (!arguments.length) {
        if (elem) {
            hooks = jQuery.valHooks[elem.type] ||
                jQuery.valHooks[elem.nodeName.toLowerCase()];
            if (hooks &&
                "get" in hooks &&
                (ret = hooks.get(elem, "value")) !== undefined) {
                return ret;
            }
            ret = elem.value;
            return typeof ret === "string" ? ret.replace(rreturn, "") : ret == null ? "" : ret;
        }
        return;
    }
    isFunction = jQuery.isFunction(value);
    return this.each(function (i) {var val, self = jQuery(this);if (this.nodeType !== 1) {return;}if (isFunction) {val = value.call(this, i, self.val());} else {val = value;}if (val == null) {val = "";} else if (typeof val === "number") {val += "";} else if (jQuery.isArray(val)) {val = jQuery.map(val, function (value) {return value == null ? "" : value + "";});}hooks = jQuery.valHooks[this.type] || jQuery.valHooks[this.nodeName.toLowerCase()];if (!hooks || !("set" in hooks) || hooks.set(this, val, "value") === undefined) {this.value = val;}});
}

什么时候应该说出输入的用户名是什么.

发生了什么？

Answer 1

使用

$("#username").val();

代替:

$("#username").val;

该val功能的全部内容正在被警告.确保实际调用该函数(with ()).

Answer 2

以下代码将函数 分配val给变量name.

    var name = $('#username').val;
    alert(name);

然后你传递函数为alert.如果要在文本框中传递值,则必须调用该函数并传递其返回值:

    var name = $('#username').val();
    alert(name);