encoding/json: can add JSEscape adn JSEscapeString function

[gopherbot]

by runner.mei:

func JSEscape(dst io.Writer, src []byte)
func JSEscapeString(dst io.Writer, src string)

[adg]

Comment 1:

What would the functions do?

[rsc]

Comment 2:

More importantly, what would they do that json.Marshal does not?

[gopherbot]

Comment 3 by runner.mei:

This is in the interests of efficiency, the scene is as follows：
buffer.WriteString(`{"a":"`)
JSEscapeString(buffer,`aa"a`)
buffer.WriteString(`", "b":"`)
JSEscapeString(buffer,`aa"a`)
buffer.WriteString(`"}`)

[rsc]

Comment 4:

You can use json.Marshal instead of JSEscapeString here.

Status changed to WorkingAsIntended.

[gopherbot]

Comment 5 by runner.mei:

yes,it is ok, but it is slower with unnecessary memory copy