semver-try-require

What's this then?

A micro module that helps you require (versions of) modules that might not be there.

Useful to test for the availability of optional and peer dependencies before working with them.

Example

So you made the typescript compiler (v2) an optional dependency. But you just want to keep running if it ain't there.

Do this:

const tryRequire = require('semver-try-require');

// import typescript if there's a version >= 2 available
const typescript = tryRequire('typescript', '>=2');

// now you can test if typescript is actually there
const lProgram = 'const cube = x => x*x*x; console.log(cube(42))';

if (typescript !== false) {
    console.log(
        typescript.transpileModule(lProgram, {}).outputText
    );
    // Result:
    //   var cube = function (x) { return x * x * x; };
    //   console.log(cube(42));
} else {
    // typescript >=2 not found - use fallback
    console.log(
        lProgram
    );
    // Result:
    //    const cube = x => x*x*x; console.log(cube(42))
}

Signature

pModulename

The name of the module to resolve.

pSemVer

A semantic version (range). Optional.

return value

The (resolved) module identified by pModuleName if:

• it is available, and
• it satisfies the semantic version range specified by pSemVer

returns false in all other cases

History

This module started to try a few non-run-of-the-mill things with the npm registry (deprecate, beta publishing, renaming). The tryRequire function in dependency-cruiser seemed like a good candidate as it was not a thing that'd be unique to dependency-cruiser, and would probably be easier to maintain on its own anyway. I named it tigerclaws-try-require until I realized the semver check was what distinguished it from the other try-require like npm modules out there.

dependency-cruiser now uses semver-try-require in the transpiler wrappers and it enables it to cruise typescript, coffeescript and livescript code without having to ship the heavy duty compilers for these languages.

License

MIT

Badge & flair section

Made with :metal: in Holland