How to use Object.values with typescript?

问题

I am trying to form a comma separated string from an object,

const data = {"Ticket-1.pdf":"8e6e8255-a6e9-4626-9606-4cd255055f71.pdf","Ticket-2.pdf":"106c3613-d976-4331-ab0c-d581576e7ca1.pdf"};
const values = Object.values(data).map(x => x.substr(0, x.length - 4));
const commaJoinedValues = values.join(',');
console.log(commaJoinedValues);

How to do this with TypeScript?

getting an error file:

severity: 'Error'
message: 'Property 'values' does not exist on type 'ObjectConstructor'.'
at: '216,27'
source: 'ts'

回答1:

using Object.keys instead.

const data = {
  a: "first",
  b: "second",
};

const values = Object.keys(data).map(key => data[key]);

const commaJoinedValues = values.join(",");
console.log(commaJoinedValues);

回答2:

Object.values() is part of ES2017, and the compile error you are getting is because you need to configure TS to use the ES2017 library. You are probably using ES6 or ES5 library in your current TS configuration.

Solution: use es2017 or es2017.object in your --lib compiler option.

For example, using tsconfig.json:

"compilerOptions": {
    "lib": ["es2017", "dom"]
}

Note that targeting ES2017 with TypeScript does not emit polyfills in the browser for ES2017 (meaning the above solves your compile error, but you can still encounter a runtime error because the browser doesn't implement ES2017 Object.values), it's up to you to polyfill your project code yourself if you want. And since Object.values is not yet well supported by all browsers (at the time of this writing) you definitely want a polyfill: core-js will do the job.

回答3:

You can use Object.values in TypeScript by doing this (<any>Object).values(data) if for some reason you can't update to ES7 in tsconfig.

回答4:

I have increased target in my tsconfig.json to enable this feature in TypeScript

{
    "compilerOptions": {
        "target": "es2017",
        ......
    }
}

回答5:

Instead of

Object.values(myObject);

use

Object["values"](myObject);

In your example case:

const values = Object["values"](data).map(x => x.substr(0, x.length - 4));

This will hide the ts compiler error.

回答6:

I just hit this exact issue with Angular 6 using the CLI and workspaces to create a library using ng g library foo.

In my case the issue was in the tsconfig.lib.json in the library folder which did not have es2017 included in the lib section.

Anyone stumbling across this issue with Angular 6 you just need to ensure that you update you tsconfig.lib.json as well as your application tsconfig.json

回答7:

Having my tslint rules configuration here always replacing the line Object["values"](myObject) with Object.values(myObject).

Two options if you have same issue:

(Object as any).values(myObject)

/*tslint:disable:no-string-literal*/
`Object["values"](myObject)`

回答8:

Simplest way is to cast the Object to any, like this:

const data = {"Ticket-1.pdf":"8e6e8255-a6e9-4626-9606-4cd255055f71.pdf","Ticket-2.pdf":"106c3613-d976-4331-ab0c-d581576e7ca1.pdf"};
const obj = <any>Object;
const values = obj.values(data).map(x => x.substr(0, x.length - 4));
const commaJoinedValues = values.join(',');
console.log(commaJoinedValues);

And voila – no compilation errors ;)

回答9:

Even simpler, use _.values from underscore.js https://underscorejs.org/#values

来源：https://stackoverflow.com/questions/42966362/how-to-use-object-values-with-typescript

标签

typescript

object