问题

I am quite new to Typescript. What does Target in tsconfig.json signify?

{
  "compilerOptions": 
  {
    "sourceMap": true,
    "target": "es5",
    "module": "commonjs",
    "jsx": "react",
    "moduleResolution": "classic",
    "lib": [ "es2015", "dom",  "es2017" ]
  }
}

回答1:

I am quite new to Typescript. What does Target in tsconfig.json signify?

target signifies which target of JavaScript should be emitted from the given TypeScript. Examples:

`target:es5`

()=>null will become function(){return null} as ES5 doesn't have arrow functions.

`target:es6`

()=>null will become ()=>null as ES6 has arrow functions.

回答2:

Target changes the JavaScript version you are compiling to.

The options are available at https://www.typescriptlang.org/docs/handbook/compiler-options.html

In the spirit of trying to better understand how the target flag changes my code I compiled some test code to each of the different versions to have a better understanding of the differences.

https://github.com/aizatto/typescript-playground/tree/master/dist/test-async-main

I'm also keeping notes of what I should be targeting depending on what environment I am looking at

https://www.aizatto.com/notes/typescript

回答3:

TypeScript docs state the target option's purpose:

Translate newer JavaScript constructs down to an older version like ECMAScript 5

[emphasis added]

If you're using IntelliSense in Visual Studio Code you may see it set a default value for target. Assume the default set errs on the side of safety and update it based on your requirements.

Not sure which version of ECMAScript to choose? Refer to the ECMAScript Compatibility Tables. Generally speaking you should target the most recent stable version of ECMAScript which doesn't cause errors in your server/runtime, minimum supported browser or graded browser support list.

来源：https://stackoverflow.com/questions/42415942/typescript-what-is-target-in-tsconfig

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