"Cannot use import statement outside a module" when using versions > 3.0

[dwalleck]

After microbundle was added to this package, I see the error SyntaxError: Cannot use import statement outside a module whenever I try to use this library. I was able to create a simple reproduction using the code from the README.
Compiling and executing this:

import { Serializable, JsonProperty } from 'typescript-json-serializer'

@Serializable()
export class LivingBeing {

    @JsonProperty() id: number;
    constructor(id: number) {
        this.id = id;
        
    }
}

results in this error

/Users/darylwalleck/repos/ts-serializer-test/node_modules/typescript-json-serializer/dist/index.modern.js:1
import"reflect-metadata";function e(){return(e=Object.assign||function(e){for(var t=1;t<arguments.length;t++){var r=arguments[t];for(var a in r)Object.prototype.hasOwnProperty.call(r,a)&&(e[a]=r[a])}return e}).apply(this,arguments)}var t;function r(e){const t=Reflect.getPrototypeOf(e);return t&&t.name?[...r(t),t.name]:[]}function a(r){return(a,n,i)=>{if(void 0===n&&a.prototype){const e=Reflect.getMetadata("design:paramtypes",a)[i];n=function(e){const t=e.toString().replace(/(\/\*[\s\S]*?\*\/|\/\/.*$)/gm,"").replace(/[\r\t\n\v\f]/g,"").replace(/( +)/g," "),r=/(?:this\.)([^\n\r\t\f\v;]+)([\s;])/gm,a=new Map,n=/(?:.*(?:constructor|function).*?(?=\())(?:\()(.+?(?=\)))/m.exec(t);if(!n||!n.length)return a;const i=n[1].replace(/ /g,"").split(",");let o;for(;o=r.exec(t);){const e=o[1].replace(/ /g,"").split("="),t=i.findIndex(t=>t===e[1]);t>-1&&a.set(t,e[0])}return a}(a.prototype.constructor).get(i),a=a.prototype,Reflect.defineMetadata("design:type",e,a,n)}let o={};const s=`api:map:${a.constructor.name}`;Reflect.hasMetadata(s,a)&&(o=Reflect.getMetadata(s,a)),o[n]=function(r,a){if(!a)return{name:r.toString(),isDictionary:!1,isNameOverridden:!1};let n;return n=typeof a===t.String?{name:a,isNameOverridden:!0}:a.name?{name:a.name,isNameOverridden:!0}:a.names&&a.names.length?{names:a.names}:{name:r.toString(),isNameOverridden:!1},n=e({},n,{beforeSerialize:a.beforeSerialize,afterSerialize:a.afterSerialize,beforeDeserialize:a.beforeDeserialize,afterDeserialize:a.afterDeserialize,isDictionary:!!a.isDictionary}),e({},n,a.predicate?{predicate:a.predicate}:{type:a.type})}(n,r),Reflect.defineMetadata(s,o,a)}}function n(e){return t=>{const a=r(t);Reflect.defineMetadata("api:map:serializable",{baseClassNames:a,options:e},t)}}function i(t,r){let a={};return t.forEach(t=>{a=e({},a,Reflect.getMetadata(`api:map:${t}`,r))}),a}function o(r,a){var n;if([null,void 0].includes(r))return r;if(void 0===a)return l(typeof r,r);const s=new a,f=s.constructor.name,{baseClassNames:p,options:u}=null!=(n=Reflect.getMetadata("api:map:serializable",a))?n:{},d=`api:map:${f}`,m=Reflect.hasMetadata(d,s);let y={};return m||p&&p.length?(y=Reflect.getMetadata(d,s),p&&p.length&&(y=e({},i(p,s),y)),Object.keys(y).forEach(e=>{const a=function(e,r,a,n,i){let s;if([null,void 0].includes(n))return n;if("names"in a){const e={};a.names.forEach(t=>e[t]=n[t]),s=e}else if("name"in a&&!a.isNameOverridden&&i){const e=i(a.name);s=n[e]}else s=n[a.name];if([null,void 0].includes(s))return s;const f=Reflect.getMetadata("design:type",e,r),p=!!f.name&&f.name.toLowerCase()===t.Array,u=a.isDictionary,d=a.predicate,m=a.beforeDeserialize,y=a.afterDeserialize;let g=a.type||f;const b=c(g);let v;if(m&&(s=m(s,e)),u){const a={};typeof s!==t.Object?(console.error(`Type '${typeof s}' is not assignable to type 'Dictionary' for property '${r}' in '${e.constructor.name}'.\n`,`Received: ${JSON.stringify(s)}`),v=void 0):(Object.keys(s).forEach(t=>{b||d?(d&&(g=d(s[t],s)),a[t]=o(s[t],g)):a[t]=l(typeof s[t],s[t],r,e.constructor.name)}),v=a)}else if(p){const t=[];Array.isArray(s)?(s.forEach(a=>{b||d?(d&&(g=d(a,s)),t.push(o(a,g))):t.push(l(typeof a,a,r,e.constructor.name))}),v=t):(console.error(`Type '${typeof s}' is not assignable to type 'Array' for property '${r}' in '${e.constructor.name}'.\n`,`Received: ${JSON.stringify(s)}`),v=void 0)}else b||d?(g=d?d(s,n):g,v=o(s,g)):v=l(g.name,s,r,e.constructor.name);return y&&(v=y(v,e)),v}(s,e,y[e],r,null==u?void 0:u.formatPropertyNames);void 0!==a&&(s[e]=a)}),s):s}function s(r,a=!0){var n;if([void 0,null].includes(r)||typeof r!==t.Object)return r;const o=`api:map:${r.constructor.name}`,{baseClassNames:l,options:f}=null!=(n=Reflect.getMetadata("api:map:serializable",r.constructor))?n:{},p=l&&l.length,u=Reflect.hasMetadata(o,r);let d={};if(!u&&!p)return r;d=Reflect.getMetadata(o,r),p&&(d=e({},i(l,r),d));const m={},y=Object.keys(r);return Object.keys(d).forEach(e=>{if(y.includes(e)){const n=d[e],i=n.beforeSerialize,o=n.afterSerialize;let l;i&&(l=r[e],r[e]=i(r[e],r));let p=function(e,r,a,n){const i=e[r],o=Reflect.getMetadata("design:type",e,r),l=!!o.name&&o.name.toLocaleLowerCase()===t.Array,f=a.predicate,p=a.type||o,u=c(p);if(i&&(u||f)){if(l)return i.map(e=>s(e,n));if(a.isDictionary){const e={};return Object.keys(i).forEach(t=>{e[t]=s(i[t],n)}),e}return s(i,n)}return p.name.toLocaleLowerCase()===t.Date&&typeof i===t.Object?i.toISOString():i}(r,e,n,a);if(o&&(p=o(p,r)),r[e]=l||r[e],n.names)n.names.forEach(e=>{(!a||a&&void 0!==p[e])&&(m[e]=p[e])});else if(!a||a&&void 0!==p)if(!n.isNameOverridden&&null!=f&&f.formatPropertyNames){const e=f.formatPropertyNames(n.name);m[e]=p}else m[n.name]=p}}),m}function c(e){return Reflect.hasOwnMetadata("api:map:serializable",e)}function l(e,r,a,n){if(null==e)return r;if(e=e.toLowerCase(),(typeof r).toLowerCase()===e)return r;const i=()=>{console.error(`Type '${typeof r}' is not assignable to type '${e}' for property '${a}' in '${n}'.\n`,`Received: ${JSON.stringify(r)}`)};switch(e){case t.String:const e=r.toString();return"[object Object]"===e?void i():e;case t.Number:const a=+r;return isNaN(a)?void i():a;case t.Boolean:return void i();case t.Date:return isNaN(Date.parse(r))?void i():new Date(r);default:return r}}!function(e){e.Array="array",e.Boolean="boolean",e.Date="date",e.Number="number",e.Object="object",e.String="string"}(t||(t={}));export{a as JsonProperty,n as Serializable,o as deserialize,s as serialize};
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at Object.compileFunction (node:vm:355:18)
    at wrapSafe (node:internal/modules/cjs/loader:1022:15)
    at Module._compile (node:internal/modules/cjs/loader:1056:27)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1121:10)
    at Module.load (node:internal/modules/cjs/loader:972:32)
    at Function.Module._load (node:internal/modules/cjs/loader:813:14)
    at Module.require (node:internal/modules/cjs/loader:996:19)
    at require (node:internal/modules/cjs/helpers:92:18)
    at Object.<anonymous> (/Users/darylwalleck/repos/ts-serializer-test/dist/index.js:13:38)
    at Module._compile (node:internal/modules/cjs/loader:1092:14)

I'm not sure if this is a bug or an issue with my tsconfig.json . Here's the config I'm using:

{
  "compilerOptions": {
    /* Visit https://aka.ms/tsconfig.json to read more about this file */
    "target": "es2020",
    "module": "commonjs",
    "strict": true,
    "outDir": "./dist",
    "rootDir": "./src",
    "sourceMap": true,
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "declaration": true,
  },
  "include": [
    "src/**/*"
  ]
}

Any feedback would be appreciated. Thanks!

[GillianPerard]

Hi, try to add, "type": "module" to the compilerOptions of your tsconfig.json.

[dwalleck]

It doesn't seem like "type" is a valid config option for compilerOptions for tsconfig.json. There is "types", but that appears to be for typing files.

[dwalleck]

If you meant in package.json, that does cause a different error if I set type to module:

file:///Users/darylwalleck/repos/ts-serializer-test/dist/index.js:10
import { Serializable, JsonProperty } from 'typescript-json-serializer';
                       ^^^^^^^^^^^^
SyntaxError: Named export 'JsonProperty' not found. The requested module 'typescript-json-serializer' is a CommonJS module, which may not support all module.exports as named exports.
CommonJS modules can always be imported via the default export, for example using:

import pkg from 'typescript-json-serializer';
const { Serializable, JsonProperty } = pkg;

However, making that change loops back around to the original error.

[GillianPerard]

I tested with your tsconfig file and it works properly :/.

What kind of project are you working on? NodeJs, React, Angular, another one?

[dwalleck]

Ugh, then this might just boil down to user error on my part. This is a TypeScript/Node.js project. I'm working on a client library for my team's API. I'm currently using Node 15.11.0 and TypeScript 4.2.3 and running OSX Big Sur. I can't think of much else that would be relevant.

[GillianPerard]

Ok and how you compile / run your code? Are you using tsc, ts-node or another one?

[dwalleck]

I just run tsc, and then node ./dist/index.js in this example. I wrapped up the sample into a repo to make sure I'm covering everything: https://github.com/dwalleck/ts-serializer-test

[GillianPerard]

Ok let me check.

What is the version of tsc? (tsc -v)

[dwalleck]

❯ tsc -v
Version 4.2.3

[GillianPerard]

In your example repository, you set the module to es2020, could you use commonjs instead?

I tried and it works.

[dwalleck]

I tried that, same error. This is completely bizarre. What version of Node are you using? I've tried this on several machines with the same result. If not that or the version of TypeScript, it seems like the problem would have to be me. I've also tried building/running the code from VSCode to remove that possibility.

[GillianPerard]

I use node 12.13.0, let me update to the LTS one.

[dwalleck]

If I roll back to 12.30.0, what you suggested works fine.

[dwalleck]

I tried 14.16.0 (the current LTS) and I'm getting a very similar error:

❯ node ./dist/index.js
(node:47836) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
/Users/darylwalleck/repos/ts-serializer-test/dist/index.js:10
import { Serializable, JsonProperty } from 'typescript-json-serializer';
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at wrapSafe (internal/modules/cjs/loader.js:979:16)
    at Module._compile (internal/modules/cjs/loader.js:1027:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
    at Module.load (internal/modules/cjs/loader.js:928:32)
    at Function.Module._load (internal/modules/cjs/loader.js:769:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47

[raravel]

I also had a similar problem.

node version

v14.16.0

project: typescript/node

/home/ec2-user/proj/sopia-api-server/node_modules/typescript-json-serializer/dist/index.modern.js:1
import"reflect-metadata";function e(){return(e=Object.assign||function(e){for(var t=1;t<arguments.length;t++){var r=arguments[t];for(var a in r)Object.prototype.hasOwnProperty.call(r,a)&&(e[a]=r[a])}return e}).apply(this,arguments)}var t;function r(e){const t=Reflect.getPrototypeOf(e);return t&&t.name?[...r(t),t.name]:[]}function a(r){return(a,n,i)=>{if(void 0===n&&a.prototype){const e=Reflect.getMetadata("design:paramtypes",a)[i];n=function(e){const t=e.toString().replace(/(\/\*[\s\S]*?\*\/|\/\/.*$)/gm,"").replace(/[\r\t\n\v\f]/g,"").replace(/( +)/g," "),r=/(?:this\.)([^\n\r\t\f\v;]+)([\s;])/gm,a=new Map,n=/(?:.*(?:constructor|function).*?(?=\())(?:\()(.+?(?=\)))/m.exec(t);if(!n||!n.length)return a;const i=n[1].replace(/ /g,"").split(",");let o;for(;o=r.exec(t);){const e=o[1].replace(/ /g,"").split("="),t=i.findIndex(t=>t===e[1]);t>-1&&a.set(t,e[0])}return a}(a.prototype.constructor).get(i),a=a.prototype,Reflect.defineMetadata("design:type",e,a,n)}let o={};const s=`api:map:${a.constructor.name}`;Reflect.hasMetadata(s,a)&&(o=Reflect.getMetadata(s,a)),o[n]=function(r,a){if(!a)return{name:r.toString(),isDictionary:!1,isNameOverridden:!1};let n;return n=typeof a===t.String?{name:a,isNameOverridden:!0}:a.name?{name:a.name,isNameOverridden:!0}:a.names&&a.names.length?{names:a.names}:{name:r.toString(),isNameOverridden:!1},n=e({},n,{beforeSerialize:a.beforeSerialize,afterSerialize:a.afterSerialize,beforeDeserialize:a.beforeDeserialize,afterDeserialize:a.afterDeserialize,isDictionary:!!a.isDictionary}),e({},n,a.predicate?{predicate:a.predicate}:{type:a.type})}(n,r),Reflect.defineMetadata(s,o,a)}}function n(e){return t=>{const a=r(t);Reflect.defineMetadata("api:map:serializable",{baseClassNames:a,options:e},t)}}function i(t,r){let a={};return t.forEach(t=>{a=e({},a,Reflect.getMetadata(`api:map:${t}`,r))}),a}function o(r,a){var n;if([null,void 0].includes(r))return r;if(void 0===a)return l(typeof r,r);const s=new a,f=s.constructor.name,{baseClassNames:p,options:u}=null!=(n=Reflect.getMetadata("api:map:serializable",a))?n:{},d=`api:map:${f}`,m=Reflect.hasMetadata(d,s);let y={};return m||p&&p.length?(y=Reflect.getMetadata(d,s),p&&p.length&&(y=e({},i(p,s),y)),Object.keys(y).forEach(e=>{const a=function(e,r,a,n,i){let s;if([null,void 0].includes(n))return n;if("names"in a){const e={};a.names.forEach(t=>e[t]=n[t]),s=e}else if("name"in a&&!a.isNameOverridden&&i){const e=i(a.name);s=n[e]}else s=n[a.name];if([null,void 0].includes(s))return s;const f=Reflect.getMetadata("design:type",e,r),p=!!f.name&&f.name.toLowerCase()===t.Array,u=a.isDictionary,d=a.predicate,m=a.beforeDeserialize,y=a.afterDeserialize;let g=a.type||f;const b=c(g);let v;if(m&&(s=m(s,e)),u){const a={};typeof s!==t.Object?(console.error(`Type '${typeof s}' is not assignable to type 'Dictionary' for property '${r}' in '${e.constructor.name}'.\n`,`Received: ${JSON.stringify(s)}`),v=void 0):(Object.keys(s).forEach(t=>{b||d?(d&&(g=d(s[t],s)),a[t]=o(s[t],g)):a[t]=l(typeof s[t],s[t],r,e.constructor.name)}),v=a)}else if(p){const t=[];Array.isArray(s)?(s.forEach(a=>{b||d?(d&&(g=d(a,s)),t.push(o(a,g))):t.push(l(typeof a,a,r,e.constructor.name))}),v=t):(console.error(`Type '${typeof s}' is not assignable to type 'Array' for property '${r}' in '${e.constructor.name}'.\n`,`Received: ${JSON.stringify(s)}`),v=void 0)}else b||d?(g=d?d(s,n):g,v=o(s,g)):v=l(g.name,s,r,e.constructor.name);return y&&(v=y(v,e)),v}(s,e,y[e],r,null==u?void 0:u.formatPropertyNames);void 0!==a&&(s[e]=a)}),s):s}function s(r,a=!0){var n;if([void 0,null].includes(r)||typeof r!==t.Object)return r;const o=`api:map:${r.constructor.name}`,{baseClassNames:l,options:f}=null!=(n=Reflect.getMetadata("api:map:serializable",r.constructor))?n:{},p=l&&l.length,u=Reflect.hasMetadata(o,r);let d={};if(!u&&!p)return r;d=Reflect.getMetadata(o,r),p&&(d=e({},i(l,r),d));const m={},y=Object.keys(r);return Object.keys(d).forEach(e=>{if(y.includes(e)){const n=d[e],i=n.beforeSerialize,o=n.afterSerialize;let l;i&&(l=r[e],r[e]=i(r[e],r));let p=function(e,r,a,n){const i=e[r],o=Reflect.getMetadata("design:type",e,r),l=!!o.name&&o.name.toLocaleLowerCase()===t.Array,f=a.predicate,p=a.type||o,u=c(p);if(i&&(u||f)){if(l)return i.map(e=>s(e,n));if(a.isDictionary){const e={};return Object.keys(i).forEach(t=>{e[t]=s(i[t],n)}),e}return s(i,n)}return p.name.toLocaleLowerCase()===t.Date&&typeof i===t.Object?i.toISOString():i}(r,e,n,a);if(o&&(p=o(p,r)),r[e]=l||r[e],n.names)n.names.forEach(e=>{(!a||a&&void 0!==p[e])&&(m[e]=p[e])});else if(!a||a&&void 0!==p)if(!n.isNameOverridden&&null!=f&&f.formatPropertyNames){const e=f.formatPropertyNames(n.name);m[e]=p}else m[n.name]=p}}),m}function c(e){return Reflect.hasOwnMetadata("api:map:serializable",e)}function l(e,r,a,n){if(null==e)return r;if(e=e.toLowerCase(),(typeof r).toLowerCase()===e)return r;const i=()=>{console.error(`Type '${typeof r}' is not assignable to type '${e}' for property '${a}' in '${n}'.\n`,`Received: ${JSON.stringify(r)}`)};switch(e){case t.String:const e=r.toString();return"[object Object]"===e?void i():e;case t.Number:const a=+r;return isNaN(a)?void i():a;case t.Boolean:return void i();case t.Date:return isNaN(Date.parse(r))?void i():new Date(r);default:return r}}!function(e){e.Array="array",e.Boolean="boolean",e.Date="date",e.Number="number",e.Object="object",e.String="string"}(t||(t={}));export{a as JsonProperty,n as Serializable,o as deserialize,s as serialize};
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at wrapSafe (internal/modules/cjs/loader.js:979:16)
    at Module._compile (internal/modules/cjs/loader.js:1027:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
    at Module.load (internal/modules/cjs/loader.js:928:32)
    at Function.Module._load (internal/modules/cjs/loader.js:769:14)
    at Module.require (internal/modules/cjs/loader.js:952:19)
    at require (internal/modules/cjs/helpers.js:88:18)
    at Object.<anonymous> (/home/ec2-user/proj/sopia-api-server/src/plugins/utils.ts:2:1)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Module.m._compile (/home/ec2-user/proj/sopia-api-server/node_modules/ts-node/src/index.ts:858:23)

I think the problem is due to the exports entry in package.json.
So, I deleted the exports item of node_modules/typescript/package.json and it works.
Or, it works even if you change index.modern.js to index.js.