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Transitionning from underscore to lodash.

To do so we use Grasp to refactor using code structure.

How does it work?

Prerequisites

$ npm install grasp -g

Run

$ ./underscore_to_lodash --help
./underscore_to_lodash <folder with some js>
        Will run all transformations available in `rules`

Operates on a single folder containing javascript code. All code will be refactored following conversions defined in ./rules.

Run several times

Code transformations are not recursive

./rules do not change code recursively.

For example, you just applied _.each → _.forEach conversion. And still, your code contains some _.each:

_.forEach(ratePlanChargeData.RatePlanChargeTier, function(ratePlanChargeTier) {
    _.each(ratePlanChargeTier, function(value, key) { /* Stuff */ });
});

Solution

Simply run ./underscore_to_lodash repetitively until it stops changing code.

⚠ Disable rules for _.omit and _.pick ⚠

$ chmod u-x rules/omit/* rules/pick/*

It prevents wierd tranformations, such as:

_.omit(o, [[["boomStick"]]])

Helper scripts

capital.py

Reads lines from standard input, then reports their occurrences.

$ cat sample
Kelly
Ash
Kelly
$ cat sample | ./capital.py
1: Ash
2: Kelly

install_lodash-migrate

Straight forward name, it installs lodash-migrate in a project for lodash → lodash migrations gone bad.

$ ./install_lodash-migrate <where to install>

lodash3_to_lodash4

Draft of conversions for lodash 3 → lodash 4 migration.

Note: For hackers, not maintained, so far.

Hack

You want to refactor some javascript, here is how.

Conversions

It is just a rule enabling to change a Javascipt call to another using Grasp. Once you make your rule:

1. Place it under rules/.
   • $ touch rules/my/rule
2. Make it executable.
   • $ chmod u+x rules/my/rule

🚀

Checks

You might want to check that your conversion is complete.

That is why after all conversions, underscore_to_lodash runs some regexes to ensure nothing is left.

You can add your regex at the end of blacklist.

Limitations

So far, calls to .chain are handled manually.