I'm a complete beginner to Typescript and am wondering if it's possible to use ES6 promises in Typescript and what I would have to do to get them to work. I'm running node 0.11.14 and am getting an error during compilation "Cannot find name 'Promise'"
This question is related to
javascript
typescript
es6-promise
As of TypeScript 2.0 you can include typings for native promises by including the following in your tsconfig.json
"compilerOptions": {
"lib": ["es5", "es2015.promise"]
}
This will include the promise declarations that comes with TypeScript without having to set the target to ES6.
If you use node.js 0.12 or above / typescript 1.4 or above, just add compiler options like:
tsc a.ts --target es6 --module commonjs
More info: https://github.com/Microsoft/TypeScript/wiki/Compiler-Options
If you use tsconfig.json
, then like this:
{
"compilerOptions": {
"module": "commonjs",
"target": "es6"
}
}
More info: https://github.com/Microsoft/TypeScript/wiki/tsconfig.json
No npm install required as ES6 Promises is native.
Node.js project -> Properties -> Typescript Build tab ECMAScript version = ECMAScript6
import http = require('http');
import fs = require('fs');
function findFolderAsync(directory : string): Promise<string> {
let p = new Promise<string>(function (resolve, reject) {
fs.stat(directory, function (err, stats) {
//Check if error defined and the error code is "not exists"
if (err && err.code === "ENOENT") {
reject("Directory does not exist");
}
else {
resolve("Directory exists");
}
});
});
return p;
}
findFolderAsync("myFolder").then(
function (msg : string) {
console.log("Promise resolved as " + msg);
},
function (msg : string) {
console.log("Promise rejected as " + msg);
}
);
A. If using "target": "es5"
and TypeScript version below 2.0:
typings install es6-promise --save --global --source dt
B. If using "target": "es5"
and TypeScript version 2.0 or higer:
"compilerOptions": {
"lib": ["es5", "es2015.promise"]
}
C. If using "target": "es6"
, there's no need to do anything.
I had to downgrade @types/core-js
to 9.36 to get it to work with "target": "es5"
set in my tsconfig.
"@types/core-js": "0.9.36",
Use the target
and lib
compiler options to compile directly to es5
without needing to install the es6-shim
. (Tested with TypeScript 2.1.4
).
In the lib section, use either es2016
or es2015.promise
.
// tsconfig.json
{
"compilerOptions": {
"target": "es5",
"lib": [
"es2015.promise",
"dom"
]
},
"include": [
"src/**/*.ts"
],
"exclude": [
"node_modules"
]
}
Use NPM to install the es6-shim
from the types organization.
npm install @types/es6-shim --save-dev
Before TypeScript 2.0, use typings to install the es6-shim
globally from DefinitelyTyped.
npm install typings --global --save-dev
typings install dt~es6-shim --global --save-dev
The typings
option uses npm
to install typings
globally and then uses typings
to install the shim. The dt~
prefix means to download the shim from DefinitelyTyped. The --global
option means that the shim's types will be available throughout the project.
https://github.com/Microsoft/TypeScript/issues/7788 - Cannot find name 'Promise' & Cannot find name 'require'
This the most recent way to do this, the above answer is outdated:
typings install --global es6-promise
Source: Stackoverflow.com