CODEWITHSUNDEEP
javascriptarraysalgorithmoopboolean
Josh
Josh

Reputation: 1267

understanding javascript advanced syntax, and object notation

So I can across this neat helper function and was getting confused with the syntax. There is a variable (bool declared as true, which appears to be an array. Its using the bracket object notation, but then going to compare if bool[j] or [i] is true yet, there is nothing adding [i] or [j] to the object map. 

const helper = (word, words) => {

    let bool = [true]; 
   //if you console.log(typeof bool) returns object ?? 




    //This comes out as an Obj at first glance I thought it was an arr, but its bracket notation
    for (var i = 1; i <= word.length; i++) {
     
        for (var j = 0; j <= i; j++) {
          //how is bool[j] being evaluated? or i if its an obj? 
            if (bool[j] === true && words[word.substring(j, i)] === true) {
                bool[i] = true;
                break;
            } else {
                bool[i] = false;
            }

        }
    }
    return console.log(bool[word.length] ? true : false);
}


helper('aa', ['aa', 'aabb', 'someotherword']);

Upvotes: 0

Views: 64

Answers (1)

גלעד ברקן
גלעד ברקן

Reputation: 23955

In JavaScript, arrays are an instance of Object and their type will register as such.

A statement like

foo[i] = 'bar'

will assign the value 'bar' at the ith zero-based index of the array (or object) foo. That's happening in the for loops in the code you posted.

var a = []

console.log(a instanceof Object)

a[3] = 4

console.log(a)

Upvotes: 2

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