lib.d.ts: Include undefined in return type of JSON.stringify() #19097
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| @@ -943,14 +943,14 @@ interface JSON { | |||
| * @param replacer A function that transforms the results. | |||
| * @param space Adds indentation, white space, and line break characters to the return-value JSON text to make it easier to read. | |||
| */ | |||
| stringify(value: any, replacer?: (key: string, value: any) => any, space?: string | number): string; | |||
| stringify(value: any, replacer?: (key: string, value: any) => any, space?: string | number): string | undefined; | |||
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I do not think you want everyone to have to handle undefined when calling JSON.stringify, it is just cases where hte input is undefined or possibly a function. for these, i would add overloads..e.g
stringify(value: number | string | boolean | null | object, replacer?: (key: string, value: any) => any, space?: string | number): string;
stringify(value: any, replacer?: (key: string, value: any) => any, space?: string | number): string | undefined;There was a problem hiding this comment.
also pinging @DanielRosenwasser and @RyanCavanaugh for feedback
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Yeah, narrowing down when undefined may appear would be great. I'm afraid this overload wouldn't catch function () {}, because it is of type object. Calling JSON.stringify(function () {}) would use the first provided overload, although the return value is undefined. Example on TypeScript Playground
Is it even possible to distinguish functions from “normal” objects in JavaScript? This is an area where I have very little knowledge.
Perhaps we can add one more overload before the other two that uses the Function type?
JSON.stringify() may return undefined if the given input value is undefined or if the input value is not serializable (like `function(){}`).
See microsoft#18879
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JSON.stringify() may return undefined if the given input value is undefined or if the input value is not serializable (like
function(){}).See #18879