I need to do something like:
if (condition) {
import something from 'something';
}
// ...
if (something) {
something.doStuff();
}
The above code does not compile; it throws SyntaxError: ... 'import' and 'export' may only appear at the top level.
I tried using System.import as shown here, but I don't know where System comes from. Is it an ES6 proposal that didn't end up being accepted? The link to "programmatic API" from that article dumps me to a deprecated docs page.
We do have dynamic imports proposal now with ECMA. This is in stage 3. This is also available as babel-preset.
Following is way to do conditional rendering as per your case.
if (condition) {
import('something')
.then((something) => {
console.log(something.something);
});
}
This basically returns a promise. Resolution of promise is expected to have the module. The proposal also have other features like multiple dynamic imports, default imports, js file import etc. You can find more information about dynamic imports here.
If you'd like, you could use require. This is a way to have a conditional require statement.
let something = null;
let other = null;
if (condition) {
something = require('something');
other = require('something').other;
}
if (something && other) {
something.doStuff();
other.doOtherStuff();
}
You can't import conditionally, but you can do the opposite: export something conditionally. It depends on your use case, so this work around might not be for you.
You can do:
api.js
import mockAPI from './mockAPI'
import realAPI from './realAPI'
const exportedAPI = shouldUseMock ? mockAPI : realAPI
export default exportedAPI
apiConsumer.js
import API from './api'
...
I use that to mock analytics libs like mixpanel, etc... because I can't have multiple builds or our frontend currently. Not the most elegant, but works. I just have a few 'if' here and there depending on the environment because in the case of mixpanel, it needs initialization.
2020 Update
You can now call the import keyword as a function (i.e. import()) to load a module at runtime. It returns a Promise that resolves to an object with the module exports.
Example:
const mymodule = await import('modulename');
const foo = mymodule.default; // Default export
const bar = mymodule.bar; // Named export
or:
import('modulename')
.then(mymodule => {
const foo = mymodule.default; // Default export
const bar = mymodule.bar; // Named export
});
See Dynamic Imports on MDN
Looks like the answer is that, as of now, you can't.
http://exploringjs.com/es6/ch_modules.html#sec_module-loader-api
I think the intent is to enable static analysis as much as possible, and conditionally imported modules break that. Also worth mentioning -- I'm using Babel, and I'm guessing that System is not supported by Babel because the module loader API didn't become an ES6 standard.
Import and Export Conditionally in JS
const value = (
await import(`${condtion ? `./file1.js` : `./file2.js`}`)
).default
export default value
Important difference if you use dynamic import Webpack mode eager:
if (normalCondition) {
// this will be included to bundle, whether you use it or not
import(...);
}
if (process.env.SOMETHING === 'true') {
// this will not be included to bundle, if SOMETHING is not 'true'
import(...);
}
require() is a way to import some module on the run time and it equally qualifies for static analysis like import if used with string literal paths. This is required by bundler to pick dependencies for the bundle.
const defaultOne = require('path/to/component').default;
const NamedOne = require('path/to/component').theName;
For dynamic module resolution with complete static analysis support, first index modules in an indexer(index.js) and import indexer in host module.
// index.js
export { default as ModuleOne } from 'path/to/module/one';
export { default as ModuleTwo } from 'path/to/module/two';
export { SomeNamedModule } from 'path/to/named/module';
// host.js
import * as indexer from 'index';
const moduleName = 'ModuleOne';
const Module = require(indexer[moduleName]);
obscuring it in an eval worked for me, hiding it from the static analyzer ...
if (typeof __CLI__ !== 'undefined') {
eval("require('fs');")
}
Conditional imports could also be achieved with a ternary and require()s:
const logger = DEBUG ? require('dev-logger') : require('logger');
This example was taken from the ES Lint global-require docs: https://eslint.org/docs/rules/global-require
I was able to achieve this using an immediately-invoked function and require statement.
const something = (() => (
condition ? require('something') : null
))();
if(something) {
something.doStuff();
}
Look at this example for clear understanding of how dynamic import works.
Dynamic Module Imports Example
To have Basic Understanding of importing and exporting Modules.
JavaScript modules Github
Javascript Modules MDN
No, you can't!
However, having bumped into that issue should make you rethink on how you organize your code.
Before ES6 modules, we had CommonJS modules which used the require() syntax. These modules were "dynamic", meaning that we could import new modules based on conditions in our code. - source: https://bitsofco.de/what-is-tree-shaking/
I guess one of the reasons they dropped that support on ES6 onward is the fact that compiling it would be very difficult or impossible.
One can go through the below link to learn more about dynamic imports
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import#dynamic_imports
I know this is not what the question is asking for, but here is my approach to use mocks when using vite. I'm sure we can do the same with webpack and others.
Suppose we have two libraries with same interface: link.js and link-mock.js, then:
In my vite.config.js
export default defineConfig(({ command, mode }) => {
const cfg = {/* ... */}
if (process.env.VITE_MOCK == 1) {
cfg.resolve.alias["./link"] = "./link-mock"; // magic is here!
}
return cfg;
}
code:
import { link } from "./link";
in console we call:
# to use the real link.js
npm run vite
# to use the mock link-mock.js
VITE_MOCK=1 npm run vite
or
package.json script
{
....
"scripts": {
"dev": "vite",
"dev-mock": "VITE_MOCK=1 vite"
}
}
Related
Is it possible to import something into a module providing a variable name while using ES6 import?
I.e. I want to import some module at a runtime depending on values provided in a config:
import something from './utils/' + variableName;
Note that I’m using Node.js, but answers must take compatibility with ECMAScript modules into consideration.
Not with the import statement. import and export are defined in such a way that they are statically analyzable, so they cannot depend on runtime information.
You are looking for the loader API (polyfill), but I'm a bit unclear about the status of the specification:
System.import('./utils/' + variableName).then(function(m) {
console.log(m);
});
Whilst this is not actually a dynamic import (eg in my circumstance, all the files I'm importing below will be imported and bundled by webpack, not selected at runtime), a pattern I've been using which may assist in some circumstances is:
import Template1 from './Template1.js';
import Template2 from './Template2.js';
const templates = {
Template1,
Template2
};
export function getTemplate (name) {
return templates[name];
}
or alternatively:
// index.js
export { default as Template1 } from './Template1';
export { default as Template2 } from './Template2';
// OtherComponent.js
import * as templates from './index.js'
...
// handy to be able to fall back to a default!
return templates[name] || templates.Template1;
I don't think I can fall back to a default as easily with require(), which throws an error if I try to import a constructed template path that doesn't exist.
Good examples and comparisons between require and import can be found here: http://www.2ality.com/2014/09/es6-modules-final.html
Excellent documentation on re-exporting from #iainastacio:
http://exploringjs.com/es6/ch_modules.html#sec_all-exporting-styles
I'm interested to hear feedback on this approach :)
There is a new specification which is called a dynamic import for ES modules.
Basically, you just call import('./path/file.js') and you're good to go. The function returns a promise, which resolves with the module if the import was successful.
async function importModule() {
try {
const module = await import('./path/module.js');
} catch (error) {
console.error('import failed');
}
}
Use cases
Use-cases include route based component importing for React, Vue etc and the ability to lazy load modules, once they are required during runtime.
Further Information
Here's is an explanation on Google Developers.
Browser compatibility (April 2020)
According to MDN it is supported by every current major browser (except IE) and caniuse.com shows 87% support across the global market share. Again no support in IE or non-chromium Edge.
In addition to Felix's answer, I'll note explicitly that this is not currently allowed by the ECMAScript 6 grammar:
ImportDeclaration :
import ImportClause FromClause ;
import ModuleSpecifier ;
FromClause :
from ModuleSpecifier
ModuleSpecifier :
StringLiteral
A ModuleSpecifier can only be a StringLiteral, not any other kind of expression like an AdditiveExpression.
I understand the question specifically asked for ES6 import in Node.js, but the following might help others looking for a more generic solution:
let variableName = "es5.js";
const something = require(`./utils/${variableName}`);
Note if you're importing an ES6 module and need to access the default export, you will need to use one of the following:
let variableName = "es6.js";
// Assigning
const defaultMethod = require(`./utils/${variableName}`).default;
// Accessing
const something = require(`./utils/${variableName}`);
something.default();
You can also use destructuring with this approach which may add more syntax familiarity with your other imports:
// Destructuring
const { someMethod } = require(`./utils/${variableName}`);
someMethod();
Unfortunately, if you want to access default as well as destructuring, you will need to perform this in multiple steps:
// ES6 Syntax
Import defaultMethod, { someMethod } from "const-path.js";
// Destructuring + default assignment
const something = require(`./utils/${variableName}`);
const defaultMethod = something.default;
const { someMethod, someOtherMethod } = something;
you can use the non-ES6 notation to do that. this is what worked for me:
let myModule = null;
if (needsToLoadModule) {
myModule = require('my-module').default;
}
I had similar problem using Vue.js: When you use variable in import(variableName) at build time Webpack doesn't know where to looking for. So you have to restrict it to known path with propriate extension like that:
let something = import("#/" + variableName + ".js")
That answer in github for the same issue was very helpful for me.
I less like this syntax, but it work:
instead of writing
import memberName from "path" + "fileName";
// this will not work!, since "path" + "fileName" need to be string literal
use this syntax:
let memberName = require("path" + "fileName");
Dynamic import() (available in Chrome 63+) will do your job. Here's how:
let variableName = 'test.js';
let utilsPath = './utils/' + variableName;
import(utilsPath).then((module) => { module.something(); });
./utils/test.js
export default () => {
doSomething...
}
call from file
const variableName = 'test';
const package = require(`./utils/${variableName}`);
package.default();
I would do it like this
function load(filePath) {
return () => System.import(`${filePath}.js`);
// Note: Change .js to your file extension
}
let A = load('./utils/' + variableName)
// Now you can use A in your module
It depends. You can use template literals in dynamic imports to import a file based on a variable.
I used dynamic imports to add .vue files to vue router. I have excluded the Home.vue view import.
const pages = [
'About',
['About', 'Team'],
]
const nodes = [
{
name: 'Home',
path: '/',
component: Home,
}
]
for (const page of pages) {
if (typeof page === 'string') {
nodes.push({
name: page,
path: `/${page}`,
component: import(`./views/${page}.vue`),
})
} else {
nodes.push({
name: _.last(page),
path: `/${page.join('/')}`,
component: import(`./views/${_.last(page)}.vue`)
})
}
}
This worked for me. I was using yarn + vite + vue on replit.
I have a config.ts and I do
module.exports = { something: 123 }
when I import like import { something } from './config.ts' I got error of config.ts' is not a module, what's the issue? my typescript is configured rightly and it's working in other places.
If you're using import { something } from './config.ts', you're using JavaScript modules, but your code in config.ts is using CommonJS modules. Some bundlers and such may let you mix them, but it's best not to.
To make config.ts a JavaScript module compatible with that import declaration (which expects a named export called something), change it to:
export const something = 123;
Or, of course, to use config.ts via CommonJS, your code using it would be:
const { something } = require("./config.ts");
...but given the error you're getting, I think your project is set up to use JavaScript modules (import/export), which here in almost 2021 is probably best (now that we have dynamic import to handle the cases where static modules don't quite do the job).
Is it possible to pass options to ES6 imports?
How do you translate this:
var x = require('module')(someoptions);
to ES6?
There is no way to do this with a single import statement, it does not allow for invocations.
So you wouldn't call it directly, but you can basically do just the same what commonjs does with default exports:
// module.js
export default function(options) {
return {
// actual module
}
}
// main.js
import m from 'module';
var x = m(someoptions);
Alternatively, if you use a module loader that supports monadic promises, you might be able to do something like
System.import('module').ap(someoptions).then(function(x) {
…
});
With the new import operator it might become
const promise = import('module').then(m => m(someoptions));
or
const x = (await import('module'))(someoptions)
however you probably don't want a dynamic import but a static one.
Concept
Here's my solution using ES6
Very much inline with #Bergi's response, this is the "template" I use when creating imports that need parameters passed for class declarations. This is used on an isomorphic framework I'm writing, so will work with a transpiler in the browser and in node.js (I use Babel with Webpack):
./MyClass.js
export default (Param1, Param2) => class MyClass {
constructor(){
console.log( Param1 );
}
}
./main.js
import MyClassFactory from './MyClass.js';
let MyClass = MyClassFactory('foo', 'bar');
let myInstance = new MyClass();
The above will output foo in a console
EDIT
Real World Example
For a real world example, I'm using this to pass in a namespace for accessing other classes and instances within a framework. Because we're simply creating a function and passing the object in as an argument, we can use it with our class declaration likeso:
export default (UIFramework) => class MyView extends UIFramework.Type.View {
getModels() {
// ...
UIFramework.Models.getModelsForView( this._models );
// ...
}
}
The importation is a bit more complicated and automagical in my case given that it's an entire framework, but essentially this is what is happening:
// ...
getView( viewName ){
//...
const ViewFactory = require(viewFileLoc);
const View = ViewFactory(this);
return new View();
}
// ...
I hope this helps!
Building on #Bergi's answer to use the debug module using es6 would be the following
// original
var debug = require('debug')('http');
// ES6
import * as Debug from 'debug';
const debug = Debug('http');
// Use in your code as normal
debug('Hello World!');
I've landed on this thread looking up for somewhat similar and would like to propose a sort of solution, at least for some cases (but see Remark below).
Use case
I have a module, that is running some instantiation logic immediately upon loading. I do not like to call this init logic outside the module (which is the same as call new SomeClass(p1, p2) or new ((p1, p2) => class SomeClass { ... p1 ... p2 ... }) and alike).
I do like that this init logic will run once, kind of a singular instantiation flow, but once per some specific parametrized context.
Example
service.js has at its very basic scope:
let context = null; // meanwhile i'm just leaving this as is
console.log('initialized in context ' + (context ? context : 'root'));
Module A does:
import * as S from 'service.js'; // console has now "initialized in context root"
Module B does:
import * as S from 'service.js'; // console stays unchanged! module's script runs only once
So far so good: service is available for both modules but was initialized only once.
Problem
How to make it run as another instance and init itself once again in another context, say in Module C?
Solution?
This is what I'm thinking about: use query parameters. In the service we'd add the following:
let context = new URL(import.meta.url).searchParams.get('context');
Module C would do:
import * as S from 'service.js?context=special';
the module will be re-imported, it's basic init logic will run and we'll see in the console:
initialized in context special
Remark: I'd myself advise to NOT practice this approach much, but leave it as the last resort. Why? Module imported more than once is more of an exception than a rule, so it is somewhat unexpected behavior and as such may confuse a consumers or even break it's own 'singleton' paradigms, if any.
I believe you can use es6 module loaders.
http://babeljs.io/docs/learn-es6/
System.import("lib/math").then(function(m) {
m(youroptionshere);
});
You just need to add these 2 lines.
import xModule from 'module';
const x = xModule('someOptions');
Here's my take on this question using the debug module as an example;
On this module's npm page, you have this:
var debug = require('debug')('http')
In the line above, a string is passed to the module that is imported, to construct. Here's how you would do same in ES6
import { debug as Debug } from 'debug'
const debug = Debug('http');
Hope this helps someone out there.
I ran into an analogous syntax issue when trying to convert some CJS (require()) code to ESM (import) - here's what worked when I needed to import Redis:
CJS
const RedisStore = require('connect-redis')(session);
ESM Equivalent
import connectRedis from 'connect-redis';
const RedisStore = connectRedis(session);
You can pass parameters in the module specifier directly:
import * as Lib from "./lib?foo=bar";
cf: https://flaming.codes/en/posts/es6-import-with-parameters
Is it possible to pass options to ES6 imports?
How do you translate this:
var x = require('module')(someoptions);
to ES6?
There is no way to do this with a single import statement, it does not allow for invocations.
So you wouldn't call it directly, but you can basically do just the same what commonjs does with default exports:
// module.js
export default function(options) {
return {
// actual module
}
}
// main.js
import m from 'module';
var x = m(someoptions);
Alternatively, if you use a module loader that supports monadic promises, you might be able to do something like
System.import('module').ap(someoptions).then(function(x) {
…
});
With the new import operator it might become
const promise = import('module').then(m => m(someoptions));
or
const x = (await import('module'))(someoptions)
however you probably don't want a dynamic import but a static one.
Concept
Here's my solution using ES6
Very much inline with #Bergi's response, this is the "template" I use when creating imports that need parameters passed for class declarations. This is used on an isomorphic framework I'm writing, so will work with a transpiler in the browser and in node.js (I use Babel with Webpack):
./MyClass.js
export default (Param1, Param2) => class MyClass {
constructor(){
console.log( Param1 );
}
}
./main.js
import MyClassFactory from './MyClass.js';
let MyClass = MyClassFactory('foo', 'bar');
let myInstance = new MyClass();
The above will output foo in a console
EDIT
Real World Example
For a real world example, I'm using this to pass in a namespace for accessing other classes and instances within a framework. Because we're simply creating a function and passing the object in as an argument, we can use it with our class declaration likeso:
export default (UIFramework) => class MyView extends UIFramework.Type.View {
getModels() {
// ...
UIFramework.Models.getModelsForView( this._models );
// ...
}
}
The importation is a bit more complicated and automagical in my case given that it's an entire framework, but essentially this is what is happening:
// ...
getView( viewName ){
//...
const ViewFactory = require(viewFileLoc);
const View = ViewFactory(this);
return new View();
}
// ...
I hope this helps!
Building on #Bergi's answer to use the debug module using es6 would be the following
// original
var debug = require('debug')('http');
// ES6
import * as Debug from 'debug';
const debug = Debug('http');
// Use in your code as normal
debug('Hello World!');
I've landed on this thread looking up for somewhat similar and would like to propose a sort of solution, at least for some cases (but see Remark below).
Use case
I have a module, that is running some instantiation logic immediately upon loading. I do not like to call this init logic outside the module (which is the same as call new SomeClass(p1, p2) or new ((p1, p2) => class SomeClass { ... p1 ... p2 ... }) and alike).
I do like that this init logic will run once, kind of a singular instantiation flow, but once per some specific parametrized context.
Example
service.js has at its very basic scope:
let context = null; // meanwhile i'm just leaving this as is
console.log('initialized in context ' + (context ? context : 'root'));
Module A does:
import * as S from 'service.js'; // console has now "initialized in context root"
Module B does:
import * as S from 'service.js'; // console stays unchanged! module's script runs only once
So far so good: service is available for both modules but was initialized only once.
Problem
How to make it run as another instance and init itself once again in another context, say in Module C?
Solution?
This is what I'm thinking about: use query parameters. In the service we'd add the following:
let context = new URL(import.meta.url).searchParams.get('context');
Module C would do:
import * as S from 'service.js?context=special';
the module will be re-imported, it's basic init logic will run and we'll see in the console:
initialized in context special
Remark: I'd myself advise to NOT practice this approach much, but leave it as the last resort. Why? Module imported more than once is more of an exception than a rule, so it is somewhat unexpected behavior and as such may confuse a consumers or even break it's own 'singleton' paradigms, if any.
I believe you can use es6 module loaders.
http://babeljs.io/docs/learn-es6/
System.import("lib/math").then(function(m) {
m(youroptionshere);
});
You just need to add these 2 lines.
import xModule from 'module';
const x = xModule('someOptions');
Here's my take on this question using the debug module as an example;
On this module's npm page, you have this:
var debug = require('debug')('http')
In the line above, a string is passed to the module that is imported, to construct. Here's how you would do same in ES6
import { debug as Debug } from 'debug'
const debug = Debug('http');
Hope this helps someone out there.
I ran into an analogous syntax issue when trying to convert some CJS (require()) code to ESM (import) - here's what worked when I needed to import Redis:
CJS
const RedisStore = require('connect-redis')(session);
ESM Equivalent
import connectRedis from 'connect-redis';
const RedisStore = connectRedis(session);
You can pass parameters in the module specifier directly:
import * as Lib from "./lib?foo=bar";
cf: https://flaming.codes/en/posts/es6-import-with-parameters
I need to do something like:
if (condition) {
import something from 'something';
}
// ...
if (something) {
something.doStuff();
}
The above code does not compile; it throws SyntaxError: ... 'import' and 'export' may only appear at the top level.
I tried using System.import as shown here, but I don't know where System comes from. Is it an ES6 proposal that didn't end up being accepted? The link to "programmatic API" from that article dumps me to a deprecated docs page.
We do have dynamic imports proposal now with ECMA. This is in stage 3. This is also available as babel-preset.
Following is way to do conditional rendering as per your case.
if (condition) {
import('something')
.then((something) => {
console.log(something.something);
});
}
This basically returns a promise. Resolution of promise is expected to have the module. The proposal also have other features like multiple dynamic imports, default imports, js file import etc. You can find more information about dynamic imports here.
If you'd like, you could use require. This is a way to have a conditional require statement.
let something = null;
let other = null;
if (condition) {
something = require('something');
other = require('something').other;
}
if (something && other) {
something.doStuff();
other.doOtherStuff();
}
You can't import conditionally, but you can do the opposite: export something conditionally. It depends on your use case, so this work around might not be for you.
You can do:
api.js
import mockAPI from './mockAPI'
import realAPI from './realAPI'
const exportedAPI = shouldUseMock ? mockAPI : realAPI
export default exportedAPI
apiConsumer.js
import API from './api'
...
I use that to mock analytics libs like mixpanel, etc... because I can't have multiple builds or our frontend currently. Not the most elegant, but works. I just have a few 'if' here and there depending on the environment because in the case of mixpanel, it needs initialization.
2020 Update
You can now call the import keyword as a function (i.e. import()) to load a module at runtime. It returns a Promise that resolves to an object with the module exports.
Example:
const mymodule = await import('modulename');
const foo = mymodule.default; // Default export
const bar = mymodule.bar; // Named export
or:
import('modulename')
.then(mymodule => {
const foo = mymodule.default; // Default export
const bar = mymodule.bar; // Named export
});
See Dynamic Imports on MDN
Looks like the answer is that, as of now, you can't.
http://exploringjs.com/es6/ch_modules.html#sec_module-loader-api
I think the intent is to enable static analysis as much as possible, and conditionally imported modules break that. Also worth mentioning -- I'm using Babel, and I'm guessing that System is not supported by Babel because the module loader API didn't become an ES6 standard.
Import and Export Conditionally in JS
const value = (
await import(`${condtion ? `./file1.js` : `./file2.js`}`)
).default
export default value
Important difference if you use dynamic import Webpack mode eager:
if (normalCondition) {
// this will be included to bundle, whether you use it or not
import(...);
}
if (process.env.SOMETHING === 'true') {
// this will not be included to bundle, if SOMETHING is not 'true'
import(...);
}
require() is a way to import some module on the run time and it equally qualifies for static analysis like import if used with string literal paths. This is required by bundler to pick dependencies for the bundle.
const defaultOne = require('path/to/component').default;
const NamedOne = require('path/to/component').theName;
For dynamic module resolution with complete static analysis support, first index modules in an indexer(index.js) and import indexer in host module.
// index.js
export { default as ModuleOne } from 'path/to/module/one';
export { default as ModuleTwo } from 'path/to/module/two';
export { SomeNamedModule } from 'path/to/named/module';
// host.js
import * as indexer from 'index';
const moduleName = 'ModuleOne';
const Module = require(indexer[moduleName]);
obscuring it in an eval worked for me, hiding it from the static analyzer ...
if (typeof __CLI__ !== 'undefined') {
eval("require('fs');")
}
Conditional imports could also be achieved with a ternary and require()s:
const logger = DEBUG ? require('dev-logger') : require('logger');
This example was taken from the ES Lint global-require docs: https://eslint.org/docs/rules/global-require
I was able to achieve this using an immediately-invoked function and require statement.
const something = (() => (
condition ? require('something') : null
))();
if(something) {
something.doStuff();
}
Look at this example for clear understanding of how dynamic import works.
Dynamic Module Imports Example
To have Basic Understanding of importing and exporting Modules.
JavaScript modules Github
Javascript Modules MDN
No, you can't!
However, having bumped into that issue should make you rethink on how you organize your code.
Before ES6 modules, we had CommonJS modules which used the require() syntax. These modules were "dynamic", meaning that we could import new modules based on conditions in our code. - source: https://bitsofco.de/what-is-tree-shaking/
I guess one of the reasons they dropped that support on ES6 onward is the fact that compiling it would be very difficult or impossible.
One can go through the below link to learn more about dynamic imports
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import#dynamic_imports
I know this is not what the question is asking for, but here is my approach to use mocks when using vite. I'm sure we can do the same with webpack and others.
Suppose we have two libraries with same interface: link.js and link-mock.js, then:
In my vite.config.js
export default defineConfig(({ command, mode }) => {
const cfg = {/* ... */}
if (process.env.VITE_MOCK == 1) {
cfg.resolve.alias["./link"] = "./link-mock"; // magic is here!
}
return cfg;
}
code:
import { link } from "./link";
in console we call:
# to use the real link.js
npm run vite
# to use the mock link-mock.js
VITE_MOCK=1 npm run vite
or
package.json script
{
....
"scripts": {
"dev": "vite",
"dev-mock": "VITE_MOCK=1 vite"
}
}