我的配置中哪些eslint规则很慢？

Question

I have a config with around 100 rules, and running eslint on my project with all these rules takes around 10 seconds. I'd like to identify the slowest rules and eliminate some of them. How do I do this? Is there any profiler tool for eslint?

Answer 1

eslint shows the spent times of rules if the environment variable TIMING is set. For example:

$ TIMING=1 eslint lib
Rule                         | Time (ms) | Relative
:----------------------------|----------:|--------:
valid-jsdoc                  |   203.798 |     6.7%
camelcase                    |   142.146 |     4.6%
no-unmodified-loop-condition |   136.811 |     4.5%
indent                       |   127.138 |     4.2%
no-undefined                 |   124.525 |     4.1%
keyword-spacing              |    85.397 |     2.8%
space-in-parens              |    76.179 |     2.5%
no-this-before-super         |    72.317 |     2.4%
no-implied-eval              |    69.945 |     2.3%
space-infix-ops              |    57.128 |     1.9%

See also the official docs on Per-rule Performance .

Answer 2

I found that removing slow rules didn't really help that much, as loading eslint and parsing files takes a while.

It is possible to use the --cache option of eslint ( docs ) to speed things up substantially.

When using eslint to "lint-as-you-type" in various editors, installing eslint_d allows running eslint as a daemon, and saves the node loading time.

On the project I'm currently working on, combining both eslint_d and --cache brought the linting time from 4+ seconds to 0.17!