Question

我尝试的是将h1样式设置为CSS_COLOR_NAMES并每秒更改一次索引，但它不起作用。

var h1 = document.querySelector("h1");

var CSS_COLOR_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"];

i = 0;
while (i<CSS_COLOR_NAMES.length){
    h1.style.color = CSS_COLOR_NAMES[i];

    setInterval(function(){
        i++;    
    }, 1000)
}

Answer 1

您不使用while循环，因为这是一个同步过程。您只需处理间隔回调中的更新，并在完成时停止间隔：

var h1 = document.querySelector("h1");

var CSS_COLOR_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"];

var i = 0;
var timer = setInterval(function() {
    h1.style.color = CSS_COLOR_NAMES[i];

    if (++i >= CSS_COLOR_NAMES.length) {
        clearInterval(timer);
    }
}, 1000);

<h1>This is the heading</h1>

另请注意var前面的i。没有它，你的代码就会成为The Horror of Implicit Globals的牺牲品.¹

或者如果你想在完成后重新开始，你可以在更新i时使用这个方便的技巧：

i = (i + 1) % CSS_COLOR_NAMES.length;

......然后不要停止间隔：

var h1 = document.querySelector("h1");

var CSS_COLOR_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"];

var i = 0;
setInterval(function() {
    h1.style.color = CSS_COLOR_NAMES[i];
    i = (i + 1) % CSS_COLOR_NAMES.length;
}, 250);

<h1>This is the heading; I've sped up the loop so we wrap sooner so you can see wrapping working.</h1>

¹（这是我贫血的小博客上的帖子。）

Answer 2

如果更改逻辑，则无法更新dom。你需要实际改变它！

var i = 0;

var interval = setInterval(function(){
    i++;
    if (!CSS_COLOR_NAMES[i]){
        clearInterval(interval);
        return;
    }
    h1.style.color = CSS_COLOR_NAMES[i];
}, 1000);

我怎样才能每秒迭代一次数组，以便h1元素每秒都会改变颜色？

2 个答案: