html - 元视口(viewport)标签中 "initial-scale"的最小值是多少？

Question

在试验 meta viewport 标签时，我注意到初始比例的任何小于 0.25 的值都被视为 0.25。例如。以下所有内容

<meta name="viewport" content="width=device-width, initial-scale=0.25">  
<meta name="viewport" content="width=device-width, initial-scale=0.1">  
<meta name="viewport" content="width=device-width, initial-scale=0.01">  
<meta name="viewport" content="width=device-width, initial-scale= ">

渲染页面相同。所以，

• Is the minimum allowed vale of "initial-scale" in meta viewport tag 0.25?
• What is the default value of initial-scale?
• Why don't initial scale take it's default value, instead of taking 0.25, when blank space is given to initial scale as initial-scale=?

Answer 1

W3C 状态

The initial-scale, minimum-scale, and maximum-scale properties

The properties are translated into 'zoom', 'min-zoom', and 'max-zoom' respectively with the following translations of values.

1. Non-negative number values are translated to values, clamped to the range [0.1, 10]
2. Negative number values are dropped
3. yes is translated to 1
4. device-width and device-height are translated to 10
5. no and unknown values are translated to 0.1

来源:https://www.w3.org/TR/css-device-adapt-1/#translate-meta-to-at-viewport

在上面给出的情况下，最小值应该是 0.1，默认值是 0.1，当没有设置值时，使用默认值。

所以您测试它的浏览器很可能使用默认值，但由于它似乎不低于 0.25，因为它不在您的测试用例中，所以不能说它是否使用默认。