這是我的問題：如何把「background-color」轉換爲rgb（）格式？
我想更改我的頁面上某個元素的背景顏色的不透明度。爲了做到這一點，我需要先將顏色轉換爲rgb（）格式。 （或提取r，g和b元素）。
here我可以看到如何將十六進制字符串轉換爲數字格式，但顏色並不總是十六進制格式。他們可以被命名爲「紅色」之類的顏色。
red ---> rgb(255, 0, 0)
#ff00ff ---> rgb(255, 0, 255)
有沒有人知道如何做到這一點？
問候。
要將colorName轉換爲RGB或十六進制，你首先需要一個字典顏色名稱和相應的價值，比你可以這樣做：
function nameToHex(name) {
return {
"aliceblue": "#f0f8ff",
"antiquewhite": "#faebd7",
"aqua": "#00ffff",
"aquamarine": "#7fffd4",
"azure": "#f0ffff",
"beige": "#f5f5dc",
"bisque": "#ffe4c4",
"black": "#000000",
"blanchedalmond": "#ffebcd",
"blue": "#0000ff",
"blueviolet": "#8a2be2",
"brown": "#a52a2a",
"burlywood": "#deb887",
"cadetblue": "#5f9ea0",
"chartreuse": "#7fff00",
"chocolate": "#d2691e",
"coral": "#ff7f50",
"cornflowerblue": "#6495ed",
"cornsilk": "#fff8dc",
"crimson": "#dc143c",
"cyan": "#00ffff",
"darkblue": "#00008b",
"darkcyan": "#008b8b",
"darkgoldenrod": "#b8860b",
"darkgray": "#a9a9a9",
"darkgreen": "#006400",
"darkkhaki": "#bdb76b",
"darkmagenta": "#8b008b",
"darkolivegreen": "#556b2f",
"darkorange": "#ff8c00",
"darkorchid": "#9932cc",
"darkred": "#8b0000",
"darksalmon": "#e9967a",
"darkseagreen": "#8fbc8f",
"darkslateblue": "#483d8b",
"darkslategray": "#2f4f4f",
"darkturquoise": "#00ced1",
"darkviolet": "#9400d3",
"deeppink": "#ff1493",
"deepskyblue": "#00bfff",
"dimgray": "#696969",
"dodgerblue": "#1e90ff",
"firebrick": "#b22222",
"floralwhite": "#fffaf0",
"forestgreen": "#228b22",
"fuchsia": "#ff00ff",
"gainsboro": "#dcdcdc",
"ghostwhite": "#f8f8ff",
"gold": "#ffd700",
"goldenrod": "#daa520",
"gray": "#808080",
"green": "#008000",
"greenyellow": "#adff2f",
"honeydew": "#f0fff0",
"hotpink": "#ff69b4",
"indianred ": "#cd5c5c",
"indigo": "#4b0082",
"ivory": "#fffff0",
"khaki": "#f0e68c",
"lavender": "#e6e6fa",
"lavenderblush": "#fff0f5",
"lawngreen": "#7cfc00",
"lemonchiffon": "#fffacd",
"lightblue": "#add8e6",
"lightcoral": "#f08080",
"lightcyan": "#e0ffff",
"lightgoldenrodyellow": "#fafad2",
"lightgrey": "#d3d3d3",
"lightgreen": "#90ee90",
"lightpink": "#ffb6c1",
"lightsalmon": "#ffa07a",
"lightseagreen": "#20b2aa",
"lightskyblue": "#87cefa",
"lightslategray": "#778899",
"lightsteelblue": "#b0c4de",
"lightyellow": "#ffffe0",
"lime": "#00ff00",
"limegreen": "#32cd32",
"linen": "#faf0e6",
"magenta": "#ff00ff",
"maroon": "#800000",
"mediumaquamarine": "#66cdaa",
"mediumblue": "#0000cd",
"mediumorchid": "#ba55d3",
"mediumpurple": "#9370d8",
"mediumseagreen": "#3cb371",
"mediumslateblue": "#7b68ee",
"mediumspringgreen": "#00fa9a",
"mediumturquoise": "#48d1cc",
"mediumvioletred": "#c71585",
"midnightblue": "#191970",
"mintcream": "#f5fffa",
"mistyrose": "#ffe4e1",
"moccasin": "#ffe4b5",
"navajowhite": "#ffdead",
"navy": "#000080",
"oldlace": "#fdf5e6",
"olive": "#808000",
"olivedrab": "#6b8e23",
"orange": "#ffa500",
"orangered": "#ff4500",
"orchid": "#da70d6",
"palegoldenrod": "#eee8aa",
"palegreen": "#98fb98",
"paleturquoise": "#afeeee",
"palevioletred": "#d87093",
"papayawhip": "#ffefd5",
"peachpuff": "#ffdab9",
"peru": "#cd853f",
"pink": "#ffc0cb",
"plum": "#dda0dd",
"powderblue": "#b0e0e6",
"purple": "#800080",
"red": "#ff0000",
"rosybrown": "#bc8f8f",
"royalblue": "#4169e1",
"saddlebrown": "#8b4513",
"salmon": "#fa8072",
"sandybrown": "#f4a460",
"seagreen": "#2e8b57",
"seashell": "#fff5ee",
"sienna": "#a0522d",
"silver": "#c0c0c0",
"skyblue": "#87ceeb",
"slateblue": "#6a5acd",
"slategray": "#708090",
"snow": "#fffafa",
"springgreen": "#00ff7f",
"steelblue": "#4682b4",
"tan": "#d2b48c",
"teal": "#008080",
"thistle": "#d8bfd8",
"tomato": "#ff6347",
"turquoise": "#40e0d0",
"violet": "#ee82ee",
"wheat": "#f5deb3",
"white": "#ffffff",
"whitesmoke": "#f5f5f5",
"yellow": "#ffff00",
"yellowgreen": "#9acd32"
}[name.toLowerCase()];
}
/////////
function hex2rgb(c) {
if (c[0] === '#') c = c.substr(1);
var r = parseInt(c.slice(0,2), 16),
g = parseInt(c.slice(2,4), 16),
b = parseInt(c.slice(4,6), 16);
return 'rgb('+ r +','+ g +','+ b +')';
}
/////////
document.querySelector("#btn").addEventListener("click", function(){
var hex = nameToHex(document.querySelector("#colorName").value);
if(!hex) return;
document.querySelector("#rgb").textContent = hex2rgb(hex);
document.querySelector("#hex").textContent = hex;
});<input id="colorName" type="text" size="8" value="cyan">
<input id="btn" type="button" value="Convert">
<div id="rgb">RGB result</div>
<div id="hex">HEX result</div>請再次閱讀問題，這隻適用於十六進制字符串。 –
好的威利。比我馬上寫出[紅色，綠色，灰色，黑色....]的var列表並轉換它的值。 –
這是可行的，但我不覺得這樣做是誠實的，我認爲必須要離開瀏覽器，因爲瀏覽器已經知道它！ –
使用window.getComputedStyle(elem, null).getPropertyValue("background-color");獲取背景色字符串。然後，檢查它是否處於所需的格式。
var name2rgb = {red: "rgb(255, 0, 0)"};）顏色名稱列表可以在網上找到。訪問this site獲取顏色名稱列表（可能是not complete）。
此功能將讓你的R和G和B，你可以用它來創建任何你想要的格式：
color_1 = resolve_color('#FFCC00');
color_2 = resolve_color('#FC0');
color_3 = resolve_color('rgb(255, 204, 0)');
color_4 = resolve_color('rgb(100%, 80%, 0%)');
在所有案例中，color_N是：
/* color_N is an array
* - color_N['red'] : 255
* - color_N['greenn'] : 204
* - color_N['red'] : 0
*/
功能
function resolve_color(color){
// return an array containing R, G and B values
if(color === 'transparent')// IE (6 and ?)
color = '#FFF';
var r,g,b;
var hex_color_pcre = new RegExp("^#[0-9a-f]{3}([0-9a-f]{3})?$",'gi');
var rgb_color_pcre = new RegExp("rgb\\(\\s*((?:[0-2]?[0-9])?[0-9])\\s*,\\s*((?:[0-2]?[0-9])?[0-9])\\s*,\\s*((?:[0-2]?[0-9])?[0-9])\\s*\\)$",'gi');
var rgb_percent_color_pcre = new RegExp("rgb\\(\\s*((?:[0-1]?[0-9])?[0-9])%\\s*,\\s*((?:[0-1]?[0-9])?[0-9])%\\s*,\\s*((?:[0-1]?[0-9])?[0-9])%\\s*\\)$",'gi');
if(color.match(hex_color_pcre)){
if(color.length == 4){
r = color.charAt(1)+""+color.charAt(1);
g = color.charAt(2)+""+color.charAt(2);
b = color.charAt(3)+""+color.charAt(3);
}
else{
r = color.charAt(1)+""+color.charAt(2);
g = color.charAt(3)+""+color.charAt(4);
b = color.charAt(5)+""+color.charAt(6);
}
r = h2d(r);
g = h2d(g);
b = h2d(b);
}
else if(color.match(rgb_color_pcre)){
r = RegExp.$1;
g = RegExp.$2;
b = RegExp.$3;
}
else if(color.match(rgb_percent_color_pcre)){
r = parseInt((RegExp.$1)*2.55);
g = parseInt((RegExp.$2)*2.55);
b = parseInt((RegExp.$3)*2.55);
}
else
return false;
var returned =[];
returned['red'] = r;
returned['green'] = g;
returned['blue'] = b;
return returned;
}
function h2d(h) {
// hex to decimal
return parseInt(h,16);
}
這不是'rgba（）'格式，即'rgb（）'格式。 – BoltClock
這並沒有什麼區別，rgb（）和rgba（）格式很容易轉換到對方。如果問題變得更清楚，我們可以編輯該問題。 –