正则表达式：将图片的相对网址补全。

Q:

I have an image tag with a src and I want to prepend a website url onto the src but only if it doesn‘t start with http://. so far I have

content.replace(/(<img *src=")(.*?)"/, ‘$1‘ + this.websiteUrl + ‘$2"‘);

but I don‘t know how to do the not starting with http:// bit

?

A:

Use a negative lookahead:

content.replace(/(<img *src=")(?!http:\/\/)(.*?)"/, ‘$1‘ + this.websiteUrl + ‘$2"‘);
					

?

my codes: