Notice the error message at the bottom: "config.ts(19,28): error TS2339: Property 'find' does not exist on type 'Answer[]". I thought all arrays would have a "find" method.
I am sure I am missing something!
5
-
Array.prototype.find() is part of ES6. Link => developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…wandering-geek– wandering-geek2015-07-13 16:41:37 +00:00Commented Jul 13, 2015 at 16:41
-
Aha! And using typescript doesn't give me bridge to that particular es6 feature. What's the closest useful es5 feature?pitosalas– pitosalas2015-07-13 16:46:26 +00:00Commented Jul 13, 2015 at 16:46
-
kkaosninja's link includes a polyfill.JJJ– JJJ2015-07-13 16:57:58 +00:00Commented Jul 13, 2015 at 16:57
-
Never heard that term 'polyfill'. I assume its standard js term of art. Where would i put that bit of code within my codebase so that it does the right thing?pitosalas– pitosalas2015-07-13 17:01:03 +00:00Commented Jul 13, 2015 at 17:01
-
Anywhere, as long as it gets run before you try to use it.JJJ– JJJ2015-07-13 17:09:32 +00:00Commented Jul 13, 2015 at 17:09
Add a comment
|
9 Answers
Since Typescript 2.0 you could also use the --lib compiler flag or a "lib": [] section in your tsconfig.js file to include ES6 features, while still targeting ES5. See https://github.com/Microsoft/TypeScript/issues/6974
In this case just include the following configuration options in your tsconfig.js:
...
"lib": [ "es6" ],
"target": "es5"
...
Comments
To answer your question it exists in TypeScript but not without some configurations.
To fix the issue you need to update your compilerOptions as follows:
"compilerOptions": {
"lib": ["es6"],
"target": "es5"
}
TypeScript 2.0
Comments
As said before, the find function is indeed part of ES6.
We fixed it by using filter instead and taking the first element of the resulting array.
Comments
Just a wrap up of all other answers. Create a tsconfig.json in you project root directory, and make sure you have this in you config:
{
... (other configs)
"compilerOptions": {
"lib": [ "es2017", "dom" ],
"target": "es5"
}
... (other configs)
}
Comments
with "lib": ["es6"] I am getting more errors, less with [ "es2017", "dom" ]:
"compilerOptions": {
"module": "es6",
"lib": [ "es2017", "dom" ]
...............
}
And it solves the problem with [].find()
Comments
I got a similar issue from a node application. where I start files from scratch. What I did to solve the issue is to install the "@types/node" package to my project. To install the package I used the following command
npm install @types/node --save-dev
This solution might be helpful for those who started to learn Typescript from the beginning.
1 Comment
Ash
Why does this work?
So... If you use Typescript then you could be using Array.prototype.find() because Typescript is a superset of javascript. BUT because you 'compile' to ES5 you get the error, because the method find is part of ES6 (ES2015), but not ES5.
It took me a while to realize of this obvious fact. It is not your typescript, it is to what you target.
1 Comment
carlin.scott
I tried all the other answers, but only changing the target to ES6 worked for me.
I guess the answer was included in the comment by kkaosninja: find is part of es6 and I am still on es5: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find
Comments
You can just force assertion by wrapping the value like this:
(value) as type[]
I rather do this and change the entire configuration of typescript to avoid get more errors.
