Replacing string in textfile with quotes and doublequotes with sed

Lets say I want to replace the following string within a textfile:

document.write(unescape("%3Cscript src='" + \ + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));

I came up with this sed command, but surprisingly nothing happens at all.

sed -i "s/document.write(unescape(\"%3Cscript src=\"\' + \\ + \"google-analytics.com\/ga.js\' type=\'text\/javascript\'%3E%3C\/script%3E\"开发者_StackOverflow社区));//g" myfile.html

Whats wrong here?

1. Backslashes should be doubly escaped, since they are expanded by both sed and the shell. Use \\\\ (becomes \\ in the shell, then \ in sed)
2. You're matching on src="', but your file contains src='".

Use

sed -i \
"s|document.write(unescape(\"%3Cscript src='\" + \\\\ + \"google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E\"));||g" \
myfile.html

I've replaced / with | to make it more readable (no more need to escape /).