The answer
Return an object with methods: function calc(a) { return { add: b => calc(a + b), subtract: b => calc(a - b), result: () => a }; }. Each method returns a new calc with the updated value. result() returns the final value.
sum(1)(2)(3) with Add and Subtract Operations
How do you extend sum to support add and subtract?
More FAQs in sum(1)(2)(3) with Add and Subtract Operations
The chain pattern (also called fluent interface or method chaining). Each method returns a new object with the updated value, allowing methods to be chained: calc(5).add(3).subtract(2).result(). Similar to jQuery and lodash.
Call the result() method: calc(5).add(3).result() returns 8. The result method returns the accumulated value and terminates the chain.
Yes. calc(10).add(5).subtract(3).multiply(2).result() returns 24. Each method returns a new calc with the updated value, so you can chain any combination of operations.
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