JavaScript应如何返回值 <href> 链接被处理？

Question

According to standards , what's the correct way to handle the return value of javascript protocol href links?

Some examples:

•  <a href='javascript:"Hello World";'> Click </a> <!-- return a String --> 

•  <a href='javascript:ThisFunctionReturnsString();'> Click </a> 

•  <a href='javascript:12345;'> Click </a> <!-- Number --> 

•  <a href='javascript:[1, 2, 3, 4, 5];'> Click </a> <!-- Array --> 

•  <a href='null;'> Click </a> <!-- null--> 

•  <a href='undefined;'> Click </a> <!-- undefined--> 

•  <a href='javascript:{};'> Click </a> <!-- Object --> 

How should a standard -compliant browser handle the return values?

How do current browsers in the wild differ from this standard behavior?

Answer 1

From Web Applications API §6.1.5 :

The following explains why clicking the links replaces the document content:

If the result of executing the script is void (there is no return value), then the URL must be treated in a manner equivalent to an HTTP resource with an HTTP 204 No Content response.

Otherwise, the URL must be treated in a manner equivalent to an HTTP resource with a 200 OK response whose Content-Type metadata is text/html and whose response body is the return value converted to a string value .

This behavior can also be demonstrated easily by simply pasting javascript:"Hello World"; in the address bar. Same goes for javascript:(function() { return "Hello World";})() .

And the following explains why only your 1 and 2 code snippets are actually doing something.

Let the script source be the string obtained using the content retrieval operation defined for javascript: URLs