Breaking down a function into a series of function calls with an argument. The following is an Javascript ES6 example of a sum function that returns the sum of the calls until no argument is passed.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | const add = (num) => { if (!num) return 0; let sum = 0 + num; const ret = (x) => { if (!x) { return sum; } else { sum += x; return ret; } }; return ret; }; alert(add(5)(6)(7)()); |