CODEWITHSUNDEEP
node.jstypescriptlodash
DARK_DUCK
DARK_DUCK

Reputation: 1777

Unable to import lodash

I'm new to TypeScript and I'm facing a problem while trying to load lodash.

Here is my code :

///<reference path="../../typings/lodash/lodash.d.ts"/>    
///<reference path="../interfaces/IScheduler.ts"/>

import _ = require('lodash');

module MyModule {

  export class LeastUsedScheduler implements IScheduler {
     /// CODE HERE
  }
}

I tried replacing the import line by :

import * as _ from lodash;

In the two cases I get : 

"error| Cannot find name 'IScheduler'."

When I remove the import directive it compiles perfectly but _ is undefined at runtime.

I also tried to put the import inside the module without success.

I'm sorry It must be a very dumb question but I can't figure it out.

Thank you

EDIT :

I understood the problem. Referencing the typing for lodash created the variable _ in the scope. That's why it compiles fine without the import line. The problem is referencing the typing does not really import lodash. That's why it fails at runtime.

When I import lodash the compilation fails because lodash is already in the scope.

Thank you for your support.

Upvotes: 2

Views: 12787

Answers (1)

Remo H. Jansen
Remo H. Jansen

Reputation: 24941

I'm not 100% about the issue but can you try the following and let me know how it goes?

///<reference path="../../typings/lodash/lodash.d.ts"/>
///<reference path="../interfaces/IScheduler.ts"/>

import _ = require("lodash");

export class LeastUsedScheduler implements IScheduler {
  doSomething(){
    _.each([],function name(parameter) {
        // ...
    });
  }
}

When compiled it looks like:

var _ = require("lodash");
var LeastUsedScheduler = (function () {
    function LeastUsedScheduler() {
    }
    LeastUsedScheduler.prototype.doSomething = function () {
        _.each([], function name(parameter) {
            throw new Error("Not implemented yet");
        });
    };
    return LeastUsedScheduler;
})();
exports.LeastUsedScheduler = LeastUsedScheduler;

If you import the module import _ = require("lodash"); but you don't use it, TypeScript will remove the import (I added the doSoemthing method for that reason).

Update: Why it didn't work?

The problem was that the module keyword is used to declare an internal module. At the same time the code was loading an external module. You should avoid mixing internal and external modules. You can learn more about the difference between internal and external modules at http://www.codebelt.com/typescript/typescript-internal-and-external-modules/.

Also, if you use internal modules avoid using the module keyword as it is deprecated and you should use the namespace keyword instead.

Upvotes: 2

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