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JavaScript JavaScript Array Iteration Methods Array Manipulation Return a Single Value from an Array with reduce()

Peter Retvari
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Peter Retvari
Full Stack JavaScript Techdegree Student 8,392 Points
Posted by Peter Retvari
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Peter Retvari
Full Stack JavaScript Techdegree Student 8,392 Points

I think you don't have to use if to solve the "Starts with G" challenge

Hi Guys,

Could you please check my code? It returns 4 and I think it's more simple:

const names = ['Gary', 'Pasan', 'Gabe', 'Treasure', 'Gengis', 'Gladys', 'Tony'];

    // Result: 4

const startsWithG = names.reduce(

  (names, name) => names + (name[0] === 'G'),

  0
);

console.log(startsWithG);

in the parenthesis you should write your statement. If it's true, the name will added to the names acc.

1 Answer

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

That's very clever! But while relying on type coercion to convert a boolean into a number works, it is a bit obscure.

I'd probably write it like this:

  (names, name) => names + (name.startsWith('G') ? 1 : 0),
Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

That's the ternary operator. If the first term evaluates to "true", then it returns the second one. Otherwise, it returns the third one. So I'm explicitly converting the boolean value (either from a comparison or the "startsWith" method) into a numeric value of 1 or 0.

For more details, see the MDN page.