Set a Field

Immutable Stateeasy

Course · Section 9: Data Structures, Modern Operators and Strings · Lecture 111: The Spread Operator (...)

Implement `setField(state, key, value)` returning a new object with `key` set to `value`.

Input: setField({"a":1}, "b", 2)

Output: {"a":1,"b":2}

Input: setField({"a":1}, "a", 9)

Output: {"a":9}

+ 1 hidden test run on Submit.

Common pitfalls

Approach & explanation (try first)

Returning { ...state, [key]: value } creates a new object with one field changed, giving React a new reference to detect the update.

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