清除 JQuery 中的文本字段值

问题描述

我知道这是一个简单的问题，但出于某种原因，这对我不起作用.我有一个每次更改下拉菜单时都会触发的功能.这是假设获取文本字段的当前值的相关代码，如果存在值，则清除它包含在 .change 函数中:

I understand this is an easy question but for some reason this just isn't working for me. I have a function that is triggered everytime a drop down menu is changed. Here is the relevant code that is suppose to grab the current value of the text field, if a value exists, clear it that is contained within the .change function:

var doc_val_check = $('#doc_title').attr("value");
    if (doc_val_check.length > 0) {
        doc_val_check == "";
    }

我觉得我错过了一些非常简单的东西.

I feel like I am missing something very simple.

推荐答案

doc_val_check == "";   // == is equality check operator

应该是

doc_val_check = "";    // = is assign operator. you need to set empty value

                       // so you need =

您可以像这样编写完整的代码:

You can write you full code like this:

var doc_val_check = $.trim( $('#doc_title').val() ); // take value of text
                                                     // field using .val()
    if (doc_val_check.length) {
        doc_val_check = ""; // this will not update your text field
    }

要使用 "" 更新文本字段，您需要尝试

To update you text field with a "" you need to try

$('#doc_title').attr('value', doc_val_check);
// or
$('doc_title').val(doc_val_check);

但我认为您不需要上述过程.

But I think you don't need above process.

$('#doc_title').val("");

注意

.val() 用于设置/获取文本字段中的值.有参数作为setter，没有参数作为getter.

Note

.val() use to set/ get value in text field. With parameter it acts as setter and without parameter acts as getter.

阅读有关.val()

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