英文解释为：直线的，线形的长度的<数>一次的，线性的
而css中正式这种意思，例如线性渐变（linear-gradient）
CSS linear-gradient() 函数用于创建一个表示两种或多种颜色线性渐变的图片。其结果属于<gradient>数据类型，是一种特别的<image>数据类型。linear-gradient( [ <angle>| to <side-or-corner>,]? <color-stop-list>)
\---------------------------------/ \----------------------------/
Definition of the gradient line List of color stops
where <side-or-corner>= [ left | right ] || [ top | bottom ]
and <color-stop-list>= [ <linear-color-stop>[, <color-hint>? ]? ]#, <linear-color-stop>
and <linear-color-stop>= <color>[ <color-stop-length>]?
and <color-stop-length>= [ <percentage>| <length>]{1,2}
and <color-hint>= [ <percentage>
栗子：
div {
background: linear-gradient(to right, red, orange, yellow, green, blue, indigo, violet)
}
![在js中定义了一个键值对数组，不遍历的情况下我直接alert这个数组名称，为甚么输出结果是[object object]?](/aiimages/%E5%9C%A8js%E4%B8%AD%E5%AE%9A%E4%B9%89%E4%BA%86%E4%B8%80%E4%B8%AA%E9%94%AE%E5%80%BC%E5%AF%B9%E6%95%B0%E7%BB%84%EF%BC%8C%E4%B8%8D%E9%81%8D%E5%8E%86%E7%9A%84%E6%83%85%E5%86%B5%E4%B8%8B%E6%88%91%E7%9B%B4%E6%8E%A5alert%E8%BF%99%E4%B8%AA%E6%95%B0%E7%BB%84%E5%90%8D%E7%A7%B0%EF%BC%8C%E4%B8%BA%E7%94%9A%E4%B9%88%E8%BE%93%E5%87%BA%E7%BB%93%E6%9E%9C%E6%98%AF%5Bobject+object%5D%3F.png)
