Grunt config functions omitted - gruntjs

Question

I am trying to define a custom function in the useminPrepare configuration, but no matter what I do, the function is eventually omitted in the build.
I have updated Node(0.10.36) and NPM(2.4.1) to the latest versions.
The config file:
useminPrepare: {
src: options.dist.dir + '/index.html',
options: {
dest: options.dist.dir + '/',
staging: options.temp.dir,
flow: {
steps: {
js: ['concat', 'uglifyjs']
},
post: {
js: [
{
name: 'concat',
createConfig: function(a,b) {
console.log(a,b);
}
},
'uglifyjs'
]
}
}
}
}
Grunt build verbose (notice createConfig is gone):
Running "useminPrepare:useminPrepare" (useminPrepare) task
Verifying property useminPrepare.useminPrepare exists in config...OK
Files: dist/index.html
Options: dest="dist/", staging=".tmp", flow={"steps":{"js":["concat","uglifyjs"]},"post":{"js":[{"name":"concat"},"uglifyjs"]}}
Going through dist/index.html to update the config
Looking for build script HTML comment blocks
Anyone have any idea?
It also omits if I specify my own parameter with a function as value (it wont get omitted if I specify a string):
name: 'concat',
test: function() {
console.log("Hello world");
},
createConfig: function() {
console.log(a,b);
}

Answer 1

I figured out what I did wrong, I should have specified the options outside my subtask, like so:
useminPreprare: {
options: {
dest: options.dist.dir + '/',
staging: options.temp.dir,
flow: {
steps: {
js: ['concat', 'uglifyjs'],
css: ['concat', 'cssmin']
},
post: {
js: [
{
name: 'concat',
createConfig: function(a,b) {
console.log(a,b);
}
},
'uglifyjs'
]
}
}
},
build: {
src: options.dist.dir + '/index.html',
}
}
Now I can execute useminPrepare with the task useminPrepare:build