Ruby-on-rails – How to “pretty” format JSON output in Ruby on Rails

eval() is not necessary. This will work fine:

var date = new Date(parseInt(jsonDate.substr(6)));

The substr() function takes out the /Date( part, and the parseInt() function gets the integer and ignores the )/ at the end. The resulting number is passed into the Date constructor.

I have intentionally left out the radix (the 2nd argument to parseInt); see my comment below.

Also, I completely agree with Rory's comment: ISO-8601 dates are preferred over this old format - so this format generally shouldn't be used for new development.

For ISO-8601 formatted JSON dates, just pass the string into the Date constructor:

var date = new Date(jsonDate); //no ugly parsing needed; full timezone support

With Python 2.6+ you can do:

echo '{"foo": "lorem", "bar": "ipsum"}' | python -m json.tool

or, if the JSON is in a file, you can do:

python -m json.tool my_json.json

if the JSON is from an internet source such as an API, you can use

curl http://my_url/ | python -m json.tool

For convenience in all of these cases you can make an alias:

alias prettyjson='python -m json.tool'

For even more convenience with a bit more typing to get it ready:

prettyjson_s() {
    echo "$1" | python -m json.tool
}

prettyjson_f() {
    python -m json.tool "$1"
}

prettyjson_w() {
    curl "$1" | python -m json.tool
}

for all the above cases. You can put this in .bashrc and it will be available every time in shell. Invoke it like prettyjson_s '{"foo": "lorem", "bar": "ipsum"}'.

Note that as @pnd pointed out in the comments below, in Python 3.5+ the JSON object is no longer sorted by default. To sort, add the --sort-keys flag to the end. I.e. ... | python -m json.tool --sort-keys.