Every coffee script file I compile seems to be missing one "group" from the "mappings" section of the source map. Here's an example:
namespace 'Codetriage', (exports) ->
class exports.TabNavigation
constructor: (options = {}) ->
@tabItem = $("a[data-toggle]")
@locationHash = location.hash
@defaultLocation() unless @locationHash
@watchHistory()
@bindDataToggleTabEvent()
@showTabLocation() if @locationHash
Compile with:
$ coffee -mc --no-header foo.coffee
Generates:
(function() {
namespace('Codetriage', function(exports) {
return exports.TabNavigation = class TabNavigation {
constructor(options = {}) {
this.tabItem = $("a[data-toggle]");
this.locationHash = location.hash;
if (!this.locationHash) {
this.defaultLocation();
}
this.watchHistory();
this.bindDataToggleTabEvent();
if (this.locationHash) {
this.showTabLocation();
}
}
};
});
}).call(this);
//# sourceMappingURL=foo.js.mapThe generated file has 20 lines (ends on }).call(this);). The source map looks like this:
{
"version": 3,
"file": "foo.js",
"sourceRoot": "",
"sources": [
"foo.coffee"
],
"names": [],
"mappings": "AAAA;EAAA,SAAA,CAAU,YAAV,EAAwB,QAAA,CAAC,OAAD,CAAA;WAChB,OAAO,CAAC,gBAAd,MAAA,cAAA;MACE,WAAa,CAAC,UAAU,CAAA,CAAX,CAAA;QACX,IAAC,CAAA,OAAD,GAAgB,CAAA,CAAE,gBAAF;QAChB,IAAC,CAAA,YAAD,GAAgB,QAAQ,CAAC;QACzB,IAAA,CAA0B,IAAC,CAAA,YAA3B;UAAA,IAAC,CAAA,eAAD,CAAA,EAAA;;QACA,IAAC,CAAA,YAAD,CAAA;QACA,IAAC,CAAA,sBAAD,CAAA;QACA,IAAsB,IAAC,CAAA,YAAvB;UAAA,IAAC,CAAA,eAAD,CAAA,EAAA;;MANW;;IADf;EADsB,CAAxB;AAAA",
"sourcesContent": [
"namespace 'Codetriage', (exports) ->\n class exports.TabNavigation\n constructor: (options = {}) ->\n @tabItem = $(\"a[data-toggle]\")\n @locationHash = location.hash\n @defaultLocation() unless @locationHash\n @watchHistory()\n @bindDataToggleTabEvent()\n @showTabLocation() if @locationHash\n\n"
]
}
It has
"AAAA;EAAA,SAAA,CAAU,YAAV,EAAwB,QAAA,CAAC,OAAD,CAAA;WAChB,OAAO,CAAC,gBAAd,MAAA,cAAA;MACE,WAAa,CAAC,UAAU,CAAA,CAAX,CAAA;QACX,IAAC,CAAA,OAAD,GAAgB,CAAA,CAAE,gBAAF;QAChB,IAAC,CAAA,YAAD,GAAgB,QAAQ,CAAC;QACzB,IAAA,CAA0B,IAAC,CAAA,YAA3B;UAAA,IAAC,CAAA,eAAD,CAAA,EAAA;;QACA,IAAC,CAAA,YAAD,CAAA;QACA,IAAC,CAAA,sBAAD,CAAA;QACA,IAAsB,IAAC,CAAA,YAAvB;UAAA,IAAC,CAAA,eAAD,CAAA,EAAA;;MANW;;IADf;EADsB,CAAxB;AAAA".count(';') + 1
# => 19
The +1 is since the last section does not end with a semicolon
19 mappings groups, which would indicate the source file only has 19 lines, even though ours has 20.
There should be a mapping for each section, but it looks like it's missing one. I'm not totally sure which line is missing though
If you use the source-map node package to parse the source map with this:
var sourceMap = require('source-map');
var fs = require('fs');
fs.readFile('./foo.js.map', 'utf8', function (err, data) {
if (err) {
return console.log(err);
}
var smc = new sourceMap.SourceMapConsumer(data);
smc.eachMapping(function(m) {
console.log(m);
});
});
It does not show a mapping for line 9:
{ source: 'foo.coffee',
generatedLine: 8,
generatedColumn: 31,
originalLine: 6,
originalColumn: 6,
name: null }
{ source: 'foo.coffee',
generatedLine: 8,
generatedColumn: 33,
originalLine: 6,
originalColumn: 6,
name: null }
// generatedLine: 9 should be here
{ source: 'foo.coffee',
generatedLine: 10,
generatedColumn: 8,
originalLine: 7,
originalColumn: 6,
name: null }
{ source: 'foo.coffee',
generatedLine: 10,
generatedColumn: 12,
originalLine: 7,
originalColumn: 7,
name: null }
Also the last line seems to be 19 instead of 20:
{ source: 'foo.coffee',
generatedLine: 19,
generatedColumn: 0,
originalLine: 1,
originalColumn: 0,
name: null }
This doesn't appear to be an issue parsing the source map in the browser, it seems that if you skip a line that chrome will default to whatever the previous line was mapped to. However I'm maintaining a tool that is trying to concatenate source maps. To do this we need to know the size of the generated sizes and we're using the number of "groupings" in a "mappings" field https://github.com/rails/sprockets/blob/341fed4f91e0dfd75f9740ee77885488db58aecd/lib/sprockets/source_map_utils.rb#L80.
Every time I concatenate two files where one of them is a coffeescript generated file the resultant offset of the second source map section is off by one.
Every coffee script file I compile seems to be missing one "group" from the "mappings" section of the source map. Here's an example:
Compile with:
Generates:
The generated file has 20 lines (ends on
}).call(this);). The source map looks like this:It has
19 mappings groups, which would indicate the source file only has 19 lines, even though ours has 20.
There should be a mapping for each section, but it looks like it's missing one. I'm not totally sure which line is missing though
If you use the
source-mapnode package to parse the source map with this:It does not show a mapping for line 9:
Also the last line seems to be 19 instead of 20:
This doesn't appear to be an issue parsing the source map in the browser, it seems that if you skip a line that chrome will default to whatever the previous line was mapped to. However I'm maintaining a tool that is trying to concatenate source maps. To do this we need to know the size of the generated sizes and we're using the number of "groupings" in a "mappings" field https://github.com/rails/sprockets/blob/341fed4f91e0dfd75f9740ee77885488db58aecd/lib/sprockets/source_map_utils.rb#L80.
Every time I concatenate two files where one of them is a coffeescript generated file the resultant offset of the second source map section is off by one.