Help to understand the logic

JavaScript
1

Tell us what’s happening:

My logic is not working properly, why compare " arr[i].indexOf(elem)==-1 " instead of "arr[i].indexOf(elem) !=-1 " ?
My brain is thinking that if " ==-1 ", the current array index element will be pushed to the newArr array contrary to skipping the element, please help me to understand this.
Thanks

Your code so far

function filteredArray(arr, elem) { 
  let newArr = [];
  // change code below this line
  for (var i=0; i < arr.length;i++){
      if (arr[i].indexOf(elem)==-1){

        newArr.push(arr[i]);
      }  
    }
  

  // change code above this line
  return newArr;
}

// change code here to test different cases:
console.log(filteredArray([ ["trumpets", 2], ["flutes", 4], ["saxophones", 2] ], 2));


function filteredArray(arr, elem) {
let newArr = [];
// change code below this line

// change code above this line
return newArr;
}

// change code here to test different cases:
console.log(filteredArray([[3, 2, 3], [1, 6, 3], [3, 13, 26], [19, 3, 9]], 3));

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User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36.

Challenge: Iterate Through All an Array’s Items Using For Loops

Link to the challenge:
https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/basic-data-structures/iterate-through-all-an-arrays-items-using-for-loops

2

I will answer to my own question, the problem was that I wasn’t understanding well the indexOf method.

3

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.

Note: Backticks are not single quotes.

markdown_Forums

4

Your code has been blurred out to avoid spoiling a full working solution for other campers who may not yet want to see a complete solution. In the future, if you post a full passing solution to a challenge and have questions about it, please surround it with [spoiler] and [/spoiler] tags on the line above and below your solution code.

Thank you.