Translating multi-line strings in javascript with django

Question

I am working on a django application, which need to support multiple languages. This application involves some amount of javascript code. In this javascript code, there are some multi-line strings, which need to be translated.

We have tried this structure:

var $text = gettext('Lorem ipsum dolor sit amet, consectetur adipisicing ' +
                    'elit, sed do eiusmod tempor incididunt ut labore et ' +
                    'dolore magna aliqua. Ut enim ad minim veniam, quis ');

This does not work. makemessages stops at the first + sign, so in the .po file it shows up as:

msgid "Lorem ipsum dolor sit amet, consectetur adipisicing "

A bit of searching on the net lead to a style guide, which recommends the format we are already using for multi-line strings. But that style is not supported by makemessages.

I tried removing the + characters at the end of the lines. Without the + characters, makemessages can find the full string, but it no longer works in the browser.

Does there exist a style for multi-line strings, which is both supported by makemessages and can be expected to work in all major browsers?

So far I have found that what makemessages is actually doing is to replace all single-quoted strings with double-quoted strings and runs the result through xgettext claiming it to be C code.

Jonas Kölker · Accepted Answer · 2014-07-04 18:10:21Z

7

The reason it doesn't work automatically is that makemessages doesn't use a real javascript parser. It does a minor transformation and applies a C parser. But in order to concatenate strings in javascript you need a + character, but in C you must not have any tokens between the strings to be concatenated.

I finally found a workaround, that works:

var $text = gettext('Lorem ipsum dolor sit amet, consectetur adipisicing ' //\
                    +
                    'elit, sed do eiusmod tempor incididunt ut labore et ' //\
                    +
                    'dolore magna aliqua. Ut enim ad minim veniam, quis ');

The javascript parser in the browser will see //\ as a comment, and find + characters between each string as needed. When using makemessages the \ character is parsed as line continuation, and both //\ as well as the + on the following line is considered to be a single comment. So the parser sees string constants separated by just a comment, and implicit string concatenation is performed.

I found this workaround by accident as I came across this piece of code from a fellow developer:

// IE8 only allows string, identifier and number keys between {}s
var parse_bool = {"null": null, "true": true, "false": false}
parse_bool[undefined] = null
parse_bool[null] = null            // using null/true/false *this* way works
parse_bool[true] = true            //  _______
parse_bool[false] = false          // ( WAT?! )
                                   //  ¯¯¯¯¯¯¯ o  ^__^
var render_bool = {}               //           o (oo)\_______
render_bool[null] = '--'           //             (__)\       )\/\
render_bool[true] = gettext('yes') //                 ||----w |
render_bool[false] = gettext('no') //                 ||     ||

When makemessages was processing this piece of javascript code, it missed the yes string.

edited Jul 4, 2014 at 18:10

Jonas Kölker

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answered Jul 4, 2014 at 18:03

kasperd

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1 Comment

Jonas Kölker Over a year ago

Speaking as the fellow developer, this is exactly why you put ASCII art cows in your code: it stress tests a lot of parsers. The fix of the sample code is of course to replace the <backslash> <slash> <backslash> cow tail with <slash> <backslash> <slash> :D

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