Problem with arrays in Javascript[solved]

Question

I expected to see Index 0 here
https://code.sololearn.com/WVx9HLRo7YM5/#js
What must I do?

Answer 1

I didn't find any solution, but I invented one, maybe it will help you. It works only with two-dimensional arrays, but you can edit it to work with any length:

/*
* @author Luis Calderon
* @description find two-dimensional arrays
* @param { Array } toFind value to find
* @return { number } Index of the found array, if not it returns -1
*/
Array.prototype.findArray = function (toFind) {
var onIndex = -1;
this.find((value, index) => {
var exist = (value[0] === toFind[0]) && (value[1] === toFind[1]);
if (exist) onIndex = index;
});

return onIndex;
}

a = [[2, 5], [1, 3], [20, 3], [0, 0], [2, 4], [1, 1], [1, 4]];

//tests
console.log(a.findArray([0, 1]));//-1
console.log(a.findArray([1, 3]));//1
console.log(a.findArray([2, 4]));//4
console.log(a.findArray([2, 5]));//0
console.log(a.findArray([0, 1]));//-1

try it:
https://code.sololearn.com/WqccsU3U2sgn/?ref=app

Answer 2

indexOf uses strict equality === and in JavaScript arrays are objects. So different but similar arrays are not equal.

When using the same array instance, it works
https://code.sololearn.com/Wp22bIIG20ES

Answer 3

grrrrrrrr
I want my python back😱😱😱

Answer 4

If the problem has been solved add "Solved" in your question heading.😊

Answer 5

Oma Falk you may have to create your own function that does that. 😉

Answer 6

Lol. Check if lodash or underscore can help with that.

Answer 7

luis calderón
finally I did it similiar

https://code.sololearn.com/WyShFT4q6l7z/?ref=app

Answer 8

HonFu
indexOf will always result in - 1
Javascript tests for ===
means identity not equality.
That exactly was my prob.

Answer 9

Ore I save coordinates in my Array. I need a solution to see, if coords already in my array.
What can I do?

Answer 10

Isn't that just a reference issue, just like in Python?

EDIT: Seems it is.

If you create the list first, it is found properly.

var a = []
var b = [1,2]
a.push(b)
alert(a)
alert(a.indexOf(b))
if (a.indexOf([1,2]) >= 0){
alert("Array found")
}}

Answer 11

Yeah, Python IS convenient, isn't it?

You have 'is' and ==, so you can ducktype your array-like objects so that they give True for comparable content AND preserve the identity of each container anyway.

Answer 12

It is tricky.

Even stuff that looks exactly the same, may behave differently between the languages.

Operator precedence being one of them. You basically have to make sure every time, when things become a little more complex.