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The JavaScript Interview Handbook: 100+ Interview Questions

Solution Review: Instance of Array?

Explore how to use the 'instanceof' operator to check if an object is an instance of Array in JavaScript. Understand prototype chain modifications by assigning Array.prototype to a constructor's prototype to pass the 'instanceof' test. This lesson clarifies type coercion and prototype inheritance through practical coding examples.

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Solution

Javascript (babel-node)
function check(){
    var tempFunc = function () {}
    tempFunc.prototype = Array.prototype
    return new tempFunc instanceof Array; 
}
console.log(check())

Explanation

The exercise required you to write some code so that the line

return new tempFunc instanceof Array

evaluates to true.

Let’s understand the original code first: ...

Javascript (babel-node)
function check(){
    var tempFunc = function () {}
    return new tempFunc instanceof Array; 
}
console.log(check())

In the ...