The JSON standard does not permit "control characters" such as a tab or newline. An example like $.parseJSON( '{ "testing":"1 2
3" }' ) will throw an error in most implementations because the JavaScript parser converts the string's tab and newline escapes into literal tab and newline; doubling the backslashes like "1\t2\n3" yields expected results. This problem is often seen when injecting JSON into a JavaScript file from a server-side language such as PHP.