for of loop isn't "looping".

Question

function containsOnlyBooleans(array){
for(i of array) {
if (typeof i === "boolean" && typeof i !== "string" && typeof i !== "number"){
return true;
}
}
return false;
}

actual = containsOnlyBooleans([true, false, true, false, 5]);
expected = true;

if (actual === expected) {
console.log("Test PASSED.");
} else {
console.error("Test FAILED. Keep trying!");
console.group("Result:");
console.log(" actual:", actual);
console.log("expected:", expected);
console.groupEnd();
}

actual = containsOnlyBooleans([true, true, true, "not a boolean"]);
expected = false;

if (actual === expected) {
console.log("Test PASSED.");
} else {
console.error("Test FAILED. Keep trying!");
console.group("Result:");
console.log(" actual:", actual);
console.log("expected:", expected);
console.groupEnd();
}

Answer 1

This seem to work

function containsOnlyBooleans( array )
{
const booleanAlike = [ "boolean", "number" ];
for( i of array )
{
if ( !booleanAlike.includes( typeof i ) )
{
return false;
}
}
return true;
}

Answer 2

Same here CamelBeatsSnake,

I was at first confused at the condition inside the for...of loop, and wasn't sure what is actually expected. I just then decided to change it a bit to follow the function's name, which I'm guessing was supposed to return `true` when all elements of <array> was "boolean alike" (made that one up though).

The thing with JS is, how it evaluate things as boolean in funny way. I've seen someone here wrote a code explaining how odd it can come about doing just that (evaluating things as boolean). Actually, I'm not all too sure how JS actually evaluates things as boolean,.

Answer 3

tristach605 Here's my ES6 version which uses the every() function. This can be done with some(). It'll be a tiny bit more difficult to read in this case but it'll perform better with big datasets.

Ipang I thought about something similar but I wasn't sure if the OP wanted only booleans because of the original logic (!== "number") but I don't know if that was a mistake by him.

const containsOnlyBooleans = values => values.every(val => typeof val === "boolean")

// test cases
console.log("true expected, actual is: ", containsOnlyBooleans([true, false, true]))

console.log("false expected, actual is: ", containsOnlyBooleans([true, "not a boolean"]))

Anyway, it can be modified easily to include numbers too.