从节点脚本获取安装的npm版本？

Question

I check the globally installed Node version in my build script:

var semver = require('semver');
var packageJson = require('./package.json');
var expectedVersion = packageJson.engines.node;

var actualVersion = process.version;
if (semver.neq(expectedVersion, actualVersion)) {
  fail('Incorrect Node version: expected ' + expectedVersion + ', but was ' + actualVersion);
}

I'd like to check the globally installed npm version in a similar manner. How can I retreive the globally installed npm version?

Answer 1

It's not pretty, but this will do the trick:

var exec = require('child_process').exec,
npmVersion;

exec('npm -v',
  function (error, stdout, stderr) {
    npmVersion = stdout;
});

Note that it's async so you'll have to do the npm comparison in the callback, but the value contained in stdout should be a valid input to semver.

Answer 2

if by "similar manner" you mean examining npm's package.json file, then you'll have to know where in the filesystem it lives. And that means knowing how npm was installed: it could be via a management tool like nvm or n , or it could be via your OS' software installation tool or package manager, or it could simply be in an arbitrary directory.

Probably the easiest thing to do is to skip trying to find npm's package.json file and instead just use node's built-in Child Process module to execute npm -v and capture the output in a variable, then compare as necessary using semver.