What is the output of the following? “`js const obj = { data: [1, 2, 3], double() { return this.data.map(function(n) { return n * this.multiplier; }); }, multiplier: 2 }; console.log(obj.double()); “`

Question

JavaScript Professional — Medium

What is the output of the following? “`js const obj = { data: [1, 2, 3], double() { return this.data.map(function(n) { return n * this.multiplier; }); }, multiplier: 2 }; console.log(obj.double()); “`

Accepted Answer

The output is [NaN, NaN, NaN] because inside the map function, `this` refers to the function scope, not the object `obj`. Therefore, `this.multiplier` is undefined, resulting in NaN values for each element in the array.