Question

我将使用javascript来创建一个函数，用于根据文本输入的值同时更改背景颜色以及文本。我已经改变了背景颜色，但无法让文本也能正常工作。

function changeBackground() {
    // The working function for changing background color.
    document.bgColor = document.getElementById("color").value;

    // The code I'd like to use for changing the text simultaneously - however it does not work.
    document.getElementById("coltext").style.color = document.getElementById("color").value;
}

查看上面的代码，当我输入实际颜色而不是“颜色”值时，文本document.getElementById("coltext").style.color = x的代码会起作用。

这是我所指的html（我知道它可怕地进行了优化，但它正在进行中）：

<form id="TheForm" style="margin-left:396px;">
    <input id="color" type="text" onchange="changeBackground();" />
    <br/><input id="submitColor" value="Submit" type="button" onclick="changeBackground();" style="margin-left:48px; margin-top:5px;" />
</form>

<span id="coltext">This text should have the same color as you put in the text box</span>

显然，不幸的是，我无法以这种方式使用代码。但无论如何我都努力尝试，除此之外，我达到了一种无限的复杂性。它应该是解决这个问题的一种简单方法，对吗？

Answer 1

你问题中的代码似乎有些混乱，所以我想给你一个我认为你试图做的例子。

首先考虑的是混合HTML，Javascript和CSS：

Why is using onClick() in HTML a bad practice?

Unobtrusive Javascript

Inline Styles vs Classes

我将删除内联内容并将其拆分为相应的文件。

接下来，我将使用“点击”事件并发布“更改”事件，因为您不清楚是否需要这两个事件。

您的函数changeBackground将背景颜色和文本颜色设置为相同的值（您的文本将不会被显示），因此我正在缓存颜色值，因为我们不需要查找颜色值DOM两次。

CSS

#TheForm {
    margin-left: 396px;
}
#submitColor {
    margin-left: 48px;
    margin-top: 5px;
}

HTML

<form id="TheForm">
    <input id="color" type="text" />
    <br/>
    <input id="submitColor" value="Submit" type="button" />
</form>
<span id="coltext">This text should have the same color as you put in the text box</span>

的Javascript

function changeBackground() {
    var color = document.getElementById("color").value; // cached

    // The working function for changing background color.
    document.bgColor = color;

    // The code I'd like to use for changing the text simultaneously - however it does not work.
    document.getElementById("coltext").style.color = color;
}

document.getElementById("submitColor").addEventListener("click", changeBackground, false);

在jsfiddle

上

<击> 资料来源：w3schools

<击>
Color Values

CSS颜色使用十六进制（十六进制）表示法定义   用于红色，绿色和蓝色值（RGB）的组合。该   可以给予其中一个光源的最低值是0（十六进制   00）。最高值为255（十六进制FF）。

~~十六进制值写为3位数字，以＃开头   标志。~~

更新：正如@Ian
所指出的那样
十六进制可以是3或6个字符长

资料来源：W3C


Numerical color values

十六进制RGB值的格式   符号是'＃'后面紧跟三个或六个   十六进制字符。三位RGB表示法（#rgb）是   通过复制数字而不是通过复制数字转换为六位数形式（#rrggbb）   添加零。例如，＃fb0扩展为＃ffbb00。这确保了   白色（#ffffff）可以用短符号（#fff）指定   删除对显示颜色深度的任何依赖。

这是一个替代函数，它将检查您的输入是否为有效的CSS Hex Color，它将仅设置文本颜色，或者如果它无效则抛出警告。

对于正则表达式测试，我将使用此模式

/^#(?:[0-9a-f]{3}){1,2}$/i

但是如果你是正则表达式匹配并希望将数字分成组，那么你需要一个不同的模式

function changeBackground() { var color = document.getElementById("color").value.trim(), rxValidHex = /^#(?:[0-9a-f]{3}){1,2}$/i; if (rxValidHex.test(color)) { document.getElementById("coltext").style.color = color; } else { alert("Invalid CSS Hex Color"); } } document.getElementById("submitColor").addEventListener("click", changeBackground, false);

在jsfiddle
上
以下是进一步修改，允许colours by name和十六进制。

function changeBackground() { var names = ["AliceBlue", "AntiqueWhite", "Aqua", "Aquamarine", "Azure", "Beige", "Bisque", "Black", "BlanchedAlmond", "Blue", "BlueViolet", "Brown", "BurlyWood", "CadetBlue", "Chartreuse", "Chocolate", "Coral", "CornflowerBlue", "Cornsilk", "Crimson", "Cyan", "DarkBlue", "DarkCyan", "DarkGoldenRod", "DarkGray", "DarkGrey", "DarkGreen", "DarkKhaki", "DarkMagenta", "DarkOliveGreen", "Darkorange", "DarkOrchid", "DarkRed", "DarkSalmon", "DarkSeaGreen", "DarkSlateBlue", "DarkSlateGray", "DarkSlateGrey", "DarkTurquoise", "DarkViolet", "DeepPink", "DeepSkyBlue", "DimGray", "DimGrey", "DodgerBlue", "FireBrick", "FloralWhite", "ForestGreen", "Fuchsia", "Gainsboro", "GhostWhite", "Gold", "GoldenRod", "Gray", "Grey", "Green", "GreenYellow", "HoneyDew", "HotPink", "IndianRed", "Indigo", "Ivory", "Khaki", "Lavender", "LavenderBlush", "LawnGreen", "LemonChiffon", "LightBlue", "LightCoral", "LightCyan", "LightGoldenRodYellow", "LightGray", "LightGrey", "LightGreen", "LightPink", "LightSalmon", "LightSeaGreen", "LightSkyBlue", "LightSlateGray", "LightSlateGrey", "LightSteelBlue", "LightYellow", "Lime", "LimeGreen", "Linen", "Magenta", "Maroon", "MediumAquaMarine", "MediumBlue", "MediumOrchid", "MediumPurple", "MediumSeaGreen", "MediumSlateBlue", "MediumSpringGreen", "MediumTurquoise", "MediumVioletRed", "MidnightBlue", "MintCream", "MistyRose", "Moccasin", "NavajoWhite", "Navy", "OldLace", "Olive", "OliveDrab", "Orange", "OrangeRed", "Orchid", "PaleGoldenRod", "PaleGreen", "PaleTurquoise", "PaleVioletRed", "PapayaWhip", "PeachPuff", "Peru", "Pink", "Plum", "PowderBlue", "Purple", "Red", "RosyBrown", "RoyalBlue", "SaddleBrown", "Salmon", "SandyBrown", "SeaGreen", "SeaShell", "Sienna", "Silver", "SkyBlue", "SlateBlue", "SlateGray", "SlateGrey", "Snow", "SpringGreen", "SteelBlue", "Tan", "Teal", "Thistle", "Tomato", "Turquoise", "Violet", "Wheat", "White", "WhiteSmoke", "Yellow", "YellowGreen"], color = document.getElementById("color").value.trim(), rxValidHex = /^#(?:[0-9a-f]{3}){1,2}$/i, formattedName = color.charAt(0).toUpperCase() + color.slice(1).toLowerCase(); if (names.indexOf(formattedName) !== -1 || rxValidHex.test(color)) { document.getElementById("coltext").style.color = color; } else { alert("Invalid CSS Color"); } } document.getElementById("submitColor").addEventListener("click", changeBackground, false);

在jsfiddle
上

Answer 2

根据您实际想要使用的事件（文本框change或按钮click），您可以尝试以下操作：

HTML：

<input id="color" type="text" onchange="changeBackground(this);" />
<br />
<span id="coltext">This text should have the same color as you put in the text box</span>

JS：

function changeBackground(obj) {
    document.getElementById("coltext").style.color = obj.value;
}

DEMO： http://jsfiddle.net/6pLUh/

按钮的一个小问题是它是表单中的提交按钮。单击时，提交表单（最终只是重新加载页面），重置JavaScript的任何更改。只需使用onchange，您就可以根据输入更改颜色。

Answer 3

document.getElementById("fname").style.borderTopColor = 'red';
document.getElementById("fname").style.borderBottomColor = 'red';

Javascript将文本和背景的颜色更改为输入值

3 个答案: