How can I get TypeScript to type-check the spread operator in React props?
This code properly flagged in TS:
<MyComponent nonexistentProp="foo" />
This code is not:
<MyComponent { ...{ nonexistentProp: "foo" }} />
It seems trivial for TS to check that improper props are not getting passed in - how can we enable this checking to ensure that we're passing in the expected props?
reactjs typescript static-analysis
asked Nov 20 at 20:20
Luke Williams
1,197928
add a comment |
This code properly flagged in TS:
<MyComponent nonexistentProp="foo" />
This code is not:
<MyComponent { ...{ nonexistentProp: "foo" }} />
It seems trivial for TS to check that improper props are not getting passed in - how can we enable this checking to ensure that we're passing in the expected props?
reactjs typescript static-analysis
asked Nov 20 at 20:20
Luke Williams
1,197928
1
I believe this is not specific to JSX and spread. This actually can be reduced toReact.createElement<MyComponentProps>(MyComponent, { nonexistentProp: "foo" })vsReact.createElement<MyComponentProps>(MyComponent, Object.assign({ nonexistentProp: "foo" }))(this is what happens internally).
– estus
Nov 20 at 21:43
add a comment |
This code properly flagged in TS:
<MyComponent nonexistentProp="foo" />
This code is not:
<MyComponent { ...{ nonexistentProp: "foo" }} />
It seems trivial for TS to check that improper props are not getting passed in - how can we enable this checking to ensure that we're passing in the expected props?
reactjs typescript static-analysis
asked Nov 20 at 20:20
Luke Williams
1,197928
This code properly flagged in TS:
<MyComponent nonexistentProp="foo" />
This code is not:
<MyComponent { ...{ nonexistentProp: "foo" }} />
It seems trivial for TS to check that improper props are not getting passed in - how can we enable this checking to ensure that we're passing in the expected props?
reactjs typescript static-analysis
reactjs typescript static-analysis
asked Nov 20 at 20:20
Luke Williams
1,197928
asked Nov 20 at 20:20
Luke Williams
1,197928
asked Nov 20 at 20:20
Luke Williams
1,197928
asked Nov 20 at 20:20
Luke Williams
1,197928
asked Nov 20 at 20:20
Luke Williams
1,197928
1,197928
1
I believe this is not specific to JSX and spread. This actually can be reduced toReact.createElement<MyComponentProps>(MyComponent, { nonexistentProp: "foo" })vsReact.createElement<MyComponentProps>(MyComponent, Object.assign({ nonexistentProp: "foo" }))(this is what happens internally).
– estus
Nov 20 at 21:43
add a comment |
1
I believe this is not specific to JSX and spread. This actually can be reduced toReact.createElement<MyComponentProps>(MyComponent, { nonexistentProp: "foo" })vsReact.createElement<MyComponentProps>(MyComponent, Object.assign({ nonexistentProp: "foo" }))(this is what happens internally).
– estus
Nov 20 at 21:43
1
1
I believe this is not specific to JSX and spread. This actually can be reduced to
React.createElement<MyComponentProps>(MyComponent, { nonexistentProp: "foo" }) vs React.createElement<MyComponentProps>(MyComponent, Object.assign({ nonexistentProp: "foo" })) (this is what happens internally).– estus
Nov 20 at 21:43
I believe this is not specific to JSX and spread. This actually can be reduced to
React.createElement<MyComponentProps>(MyComponent, { nonexistentProp: "foo" }) vs React.createElement<MyComponentProps>(MyComponent, Object.assign({ nonexistentProp: "foo" })) (this is what happens internally).– estus
Nov 20 at 21:43
add a comment |
1 Answer
1
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I suspect this type checking is subject to the same constraints as regular TypeScript code:
interface Contract {
a: string;
}
const allowed: Contract = {
a: "bc",
};
const notAllowed: Contract = {
a: "bc",
b: "dc",
};
const aboutToBeAllowed = {
a: "bc",
b: "dc",
};
const alsoAllowed: Contract = aboutToBeAllowed;
The problem shown here is that TypeScript has it's limitations, in that it's a structural type system.
It is only able to enforce the constraints that us humans think it should be doing in all cases during an object literal assignment (see notAllowed assignment).
The alsoAllowed case is essentially the same as the notAllowed variant, but it works. This is because the anonymous object satisfies the Contract constraints.
Similarly, in your TSX example, this is essentially the same behavior as regular TypeScript:
interface Props { a: string; };
const MyComponent: React.SFC<Props> = (props) => <div />;
const myCompOk1 = <MyComponent a="ab" />;
const myCompBad1 = <MyComponent a="ab" b="cd" />;
const anonPropsNoExtra = { a: "bc" };
const myCompOk2 = <MyComponent {...anonPropsNoExtra} />;
const anonPropsWithExtra = { a: "bc", b: "cd" };
const myCompOk3 = <MyComponent {...anonPropsWithExtra} />;
I don't believe it's possible for it to enforce it the way you're looking for
answered Nov 21 at 5:14
Alex
1,9841415
Ok - interesting, thank you for the background. I'm able to get what I need by refactoring a bit to type-check the object before spreading it into the props.
– Luke Williams
Dec 3 at 19:14
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
I suspect this type checking is subject to the same constraints as regular TypeScript code:
interface Contract {
a: string;
}
const allowed: Contract = {
a: "bc",
};
const notAllowed: Contract = {
a: "bc",
b: "dc",
};
const aboutToBeAllowed = {
a: "bc",
b: "dc",
};
const alsoAllowed: Contract = aboutToBeAllowed;
The problem shown here is that TypeScript has it's limitations, in that it's a structural type system.
It is only able to enforce the constraints that us humans think it should be doing in all cases during an object literal assignment (see notAllowed assignment).
The alsoAllowed case is essentially the same as the notAllowed variant, but it works. This is because the anonymous object satisfies the Contract constraints.
Similarly, in your TSX example, this is essentially the same behavior as regular TypeScript:
interface Props { a: string; };
const MyComponent: React.SFC<Props> = (props) => <div />;
const myCompOk1 = <MyComponent a="ab" />;
const myCompBad1 = <MyComponent a="ab" b="cd" />;
const anonPropsNoExtra = { a: "bc" };
const myCompOk2 = <MyComponent {...anonPropsNoExtra} />;
const anonPropsWithExtra = { a: "bc", b: "cd" };
const myCompOk3 = <MyComponent {...anonPropsWithExtra} />;
I don't believe it's possible for it to enforce it the way you're looking for
answered Nov 21 at 5:14
Alex
1,9841415
Ok - interesting, thank you for the background. I'm able to get what I need by refactoring a bit to type-check the object before spreading it into the props.
– Luke Williams
Dec 3 at 19:14
add a comment |
I suspect this type checking is subject to the same constraints as regular TypeScript code:
interface Contract {
a: string;
}
const allowed: Contract = {
a: "bc",
};
const notAllowed: Contract = {
a: "bc",
b: "dc",
};
const aboutToBeAllowed = {
a: "bc",
b: "dc",
};
const alsoAllowed: Contract = aboutToBeAllowed;
The problem shown here is that TypeScript has it's limitations, in that it's a structural type system.
It is only able to enforce the constraints that us humans think it should be doing in all cases during an object literal assignment (see notAllowed assignment).
The alsoAllowed case is essentially the same as the notAllowed variant, but it works. This is because the anonymous object satisfies the Contract constraints.
Similarly, in your TSX example, this is essentially the same behavior as regular TypeScript:
interface Props { a: string; };
const MyComponent: React.SFC<Props> = (props) => <div />;
const myCompOk1 = <MyComponent a="ab" />;
const myCompBad1 = <MyComponent a="ab" b="cd" />;
const anonPropsNoExtra = { a: "bc" };
const myCompOk2 = <MyComponent {...anonPropsNoExtra} />;
const anonPropsWithExtra = { a: "bc", b: "cd" };
const myCompOk3 = <MyComponent {...anonPropsWithExtra} />;
I don't believe it's possible for it to enforce it the way you're looking for
answered Nov 21 at 5:14
Alex
1,9841415
Ok - interesting, thank you for the background. I'm able to get what I need by refactoring a bit to type-check the object before spreading it into the props.
– Luke Williams
Dec 3 at 19:14
add a comment |
I suspect this type checking is subject to the same constraints as regular TypeScript code:
interface Contract {
a: string;
}
const allowed: Contract = {
a: "bc",
};
const notAllowed: Contract = {
a: "bc",
b: "dc",
};
const aboutToBeAllowed = {
a: "bc",
b: "dc",
};
const alsoAllowed: Contract = aboutToBeAllowed;
The problem shown here is that TypeScript has it's limitations, in that it's a structural type system.
It is only able to enforce the constraints that us humans think it should be doing in all cases during an object literal assignment (see notAllowed assignment).
The alsoAllowed case is essentially the same as the notAllowed variant, but it works. This is because the anonymous object satisfies the Contract constraints.
Similarly, in your TSX example, this is essentially the same behavior as regular TypeScript:
interface Props { a: string; };
const MyComponent: React.SFC<Props> = (props) => <div />;
const myCompOk1 = <MyComponent a="ab" />;
const myCompBad1 = <MyComponent a="ab" b="cd" />;
const anonPropsNoExtra = { a: "bc" };
const myCompOk2 = <MyComponent {...anonPropsNoExtra} />;
const anonPropsWithExtra = { a: "bc", b: "cd" };
const myCompOk3 = <MyComponent {...anonPropsWithExtra} />;
I don't believe it's possible for it to enforce it the way you're looking for
answered Nov 21 at 5:14
Alex
1,9841415
I suspect this type checking is subject to the same constraints as regular TypeScript code:
interface Contract {
a: string;
}
const allowed: Contract = {
a: "bc",
};
const notAllowed: Contract = {
a: "bc",
b: "dc",
};
const aboutToBeAllowed = {
a: "bc",
b: "dc",
};
const alsoAllowed: Contract = aboutToBeAllowed;
The problem shown here is that TypeScript has it's limitations, in that it's a structural type system.
It is only able to enforce the constraints that us humans think it should be doing in all cases during an object literal assignment (see notAllowed assignment).
The alsoAllowed case is essentially the same as the notAllowed variant, but it works. This is because the anonymous object satisfies the Contract constraints.
Similarly, in your TSX example, this is essentially the same behavior as regular TypeScript:
interface Props { a: string; };
const MyComponent: React.SFC<Props> = (props) => <div />;
const myCompOk1 = <MyComponent a="ab" />;
const myCompBad1 = <MyComponent a="ab" b="cd" />;
const anonPropsNoExtra = { a: "bc" };
const myCompOk2 = <MyComponent {...anonPropsNoExtra} />;
const anonPropsWithExtra = { a: "bc", b: "cd" };
const myCompOk3 = <MyComponent {...anonPropsWithExtra} />;
I don't believe it's possible for it to enforce it the way you're looking for
answered Nov 21 at 5:14
Alex
1,9841415
answered Nov 21 at 5:14
Alex
1,9841415
answered Nov 21 at 5:14
Alex
1,9841415
answered Nov 21 at 5:14
Alex
1,9841415
1,9841415
Ok - interesting, thank you for the background. I'm able to get what I need by refactoring a bit to type-check the object before spreading it into the props.
– Luke Williams
Dec 3 at 19:14
add a comment |
Ok - interesting, thank you for the background. I'm able to get what I need by refactoring a bit to type-check the object before spreading it into the props.
– Luke Williams
Dec 3 at 19:14
Ok - interesting, thank you for the background. I'm able to get what I need by refactoring a bit to type-check the object before spreading it into the props.
– Luke Williams
Dec 3 at 19:14
Ok - interesting, thank you for the background. I'm able to get what I need by refactoring a bit to type-check the object before spreading it into the props.
– Luke Williams
Dec 3 at 19:14
add a comment |
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1
I believe this is not specific to JSX and spread. This actually can be reduced to
React.createElement<MyComponentProps>(MyComponent, { nonexistentProp: "foo" })vsReact.createElement<MyComponentProps>(MyComponent, Object.assign({ nonexistentProp: "foo" }))(this is what happens internally).– estus
Nov 20 at 21:43