sum(1)(2)(3) with Add and Subtract Operations
Extending the sum function to support multiple operations.
sum(1)(2)(3) with Add and Subtract Operations
Extended Version
function calc(a) { return { add: function (b) { return calc(a + b); }, subtract: function (b) { return calc(a - b); }, multiply: function (b) { return calc(a * b); }, result: function () { return a; }, }; } calc(5).add(3).subtract(2).result(); // 6
How It Works
Each method returns a new calc object with the updated value. The result method returns the final value.
Chain Pattern
calc(10) .add(5) // 15 .subtract(3) // 12 .multiply(2) // 24 .result(); // 24
The Takeaway
Extended sum: return an object with methods (add, subtract, multiply, result). Each method returns a new calc object with the updated value. This is the chain pattern (like jQuery, lodash). The result method terminates and returns the value.
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.
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.
Each method closes over the current value (a). add returns calc(a + b), which creates a new calc with the new value. The closure keeps the value alive between chained calls.
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