更改文本框输入的背景颜色在为空时不起作用 [英] Changing background color of text box input not working when empty

问题描述

如果输入为空，我很难使用此 javascript 代码更改文本输入的背景颜色.

I am having a tough time with this javascript code to change the background color of a text input if the input is empty.

代码如下:

function checkFilled() {
    var inputVal = document.getElementById("subEmail").value;
    if (inputVal == "") {
        inputVal.style.backgroundColor = "yellow";
                }
        }

示例:http://jsfiddle.net/2Xgfr/

我希望文本框一开始是黄色的.

I would expect the textbox to come out yellow at the beginning.

推荐答案

DEMO --> http://jsfiddle.net/2Xgfr/829/

HTML

<input type="text" id="subEmail" onchange="checkFilled();">

JavaScript

 function checkFilled() {
    var inputVal = document.getElementById("subEmail");
    if (inputVal.value == "") {
        inputVal.style.backgroundColor = "yellow";
    }
    else{
        inputVal.style.backgroundColor = "";
    }
}

checkFilled();

注意:您正在检查值并将颜色设置为不允许的值，这就是它给您错误的原因.像上面那样尝试.

Note: You were checking value and setting color to value which is not allowed, that's why it was giving you errors. try like the above.

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