javascript - querySelectorAll 语法无效

Question

尝试在错误控制台中执行这 2 个代码块:

第一个。输出节点列表。

var selector = "*[data-type=day][data-day='23']";
var a = document.querySelectorAll( selector );
alert( a );

第二个。产生错误。

var selector = "*[data-type=day][data-day=23]";
var a = document.querySelectorAll( selector );
alert( a );

为什么 data-type=day 是正确的语法而 data-day=23 不是？属性值是否应始终包装为 data-type='day'？

这是在第二种情况下引发的异常:

[Exception... "An invalid or illegal string was specified" code: "12" nsresult: "0x8053000c (SyntaxError)" ]

Answer 1

浏览器紧跟着the specification其中说:

Attribute values must be CSS identifiers or strings.

及identifiers :

In CSS, identifiers (including element names, classes, and IDs in selectors) can contain only the characters [a-zA-Z0-9] and ISO 10646 characters U+00A0 and higher, plus the hyphen (-) and the underscore (_); they cannot start with a digit…

所以23(以数字开头)必须表示为a string :

Strings can either be written with double quotes or with single quotes