"Guess" based on the structure of the data (for example, an array of two-member arrays).Serialize the entire object to a string and prefix it with a type tag.log (map2 ) // Map īecause JSON has no syntax space for annotating type metadata, in order to revive values that are not plain objects, you have to consider one of the following: isArray (value ) ? new Map (value ) : value, ) Ĭonsole. parse (jsonText, ( key, value ) =>Īrray. const map = new Map (, ,, ] ) const jsonText = JSON. We can use the replacer to specify the entries to be serialized. Js // Maps are normally serialized as objects with no properties. If you return another value from reviver, that value will completely replace the originally parsed value. ![]() For other valid JSON values, reviver works similarly and is called once with an empty string as the key and the value itself as the value. Similar to the replacer parameter of JSON.stringify(), for arrays and objects, reviver will be last called on the root value with an empty string as the key and the root object as the value. If the reviver only transforms some values and not others, be certain to return all untransformed values as-is - otherwise, they will be deleted from the resulting object. Otherwise, the property is redefined to be the return value. ![]() If the reviver function returns undefined (or returns no value - for example, if execution falls off the end of the function), the property is deleted from the object. ![]() The reviver is called with the object containing the property being processed as this (unless you define the reviver as an arrow function, in which case there's no separate this binding) and two arguments: key and value, representing the property name as a string (even for arrays) and the property value. Specifically, the computed value and all its properties (in a depth-first fashion, beginning with the most nested properties and proceeding to the original value itself) are individually run through the reviver. If a reviver is specified, the value computed by parsing is transformed before being returned.
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