js array is array code example

Example 1: javascript check if is array

var colors=["red","green","blue"];

if(Array.isArray(colors)){
    //colors is an array
}

Example 2: javascript typeof array

Array.isArray(arr)

Example 3: js check if is array

if(Array.isArray(colors)){
    //colors is an array
}

Example 4: isarray

Array.isArray([1, 2, 3]);  // true
Array.isArray({foo: 123}); // false
Array.isArray('foobar');   // false
Array.isArray(undefined);  // false

Example 5: array from js

//Array.from() lets you create Arrays from array-like objects
//(objects with a length property and indexed elements);
//and also:

//More clearly, Array.from(obj, mapFn, thisArg)
//has the same result as Array.from(obj).map(mapFn, thisArg), 
//except that it does not create an intermediate array.
//Basically, it's a declaration that overrides the length property of the method
//(so that it has to be used with the same name length),
//setting it with the same value of the given variable. 
//The values are still undefined, it's just a different notation. Take a look:

console.log(Array.from(length, (_,i) => i));
// It doesn't works with non-iterables
// In this case we are passing an integer

console.log(Array.from({LENGTH}, (_,i) => i));
// It doesn't work with a property name different from "length"

console.log(Array.from({length}, (_,i) => i));
// It works because overrides the .length property of the array
// The method Array.from() assumes that the property...
// ...is referring to an iterable (also if not declared) 

console.log(Array.from(Array(length), (_,i) => i));
// This is the demonstration of the above assertion
// In this case we are using a declared array through...
// ...an instance of the straight method Array()...
// ...that accepts an integer as value

//in case any one reads this a got this from er0s in edabit