Need Help Array for loop If else statement

Question

need help with For loop array , i want the opposite data of function, but when i try arr[i] != elem it print out all the array; and if i try arr[i] == elem , it give me the array that i don't want; still don't understand why it not work with != (not equal).

function filteredArray(arr, elem) {
let newArr = [];
// change code below this line
for(let i = arr.length -1; i >= 0 ; i--) {
  for(let j = arr[i].length-1;j >= 0;j--) {
    if(arr[i][j] !== elem) {
        newArr.push(arr[i]);
     }
   }
 }
 // change code above this line
  return newArr;
}

console.log(filteredArray([ ["trumpets", 2], ["flutes", 4], ["saxophones", 2] ], 2));

the result i want is ["flutes", 4] sorry if this have been asking by others, i have been looking for the answer trough google , but can not find it.

thanks for the help

Arrays and objects are not comparable like that. Arrays already offer a built in filter function. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — JavaScript
– JavaScript, Commented Sep 4, 2018 at 12:01

user3297291 · Accepted Answer · 2018-09-04 13:24:40Z

1

You were nearly there!

You were checking against every value in the array. I.e.: 2 !== "trumpets" and 2 !== 2. Therefore, all arrays got pushed, because all arrays had a string value that will never match.

Remove the second loop and check for the second value of the inner array explicitly:

function filteredArray(arr, elem) {
let newArr = [];
// change code below this line
for(let i = arr.length -1; i >= 0 ; i--) {
    if(arr[i][1] !== elem) {
        newArr.push(arr[i]);
     }
 }
 // change code above this line
  return newArr;
}

console.log(filteredArray([ ["trumpets", 2], ["flutes", 4], ["saxophones", 2] ], 2));

The snippet above shows the error in your current approach, but doesn't provide a very re-usable function. If you want to check whether an array includes a value, it's easiest to fall back to some of the built in array methods:

function filteredArray(arr, elem) {
  return arr.filter(values => !values.includes(elem));
}

console.log(filteredArray([ ["trumpets", 2], ["flutes", 4], ["saxophones", 2] ], 2));

console.log(filteredArray([ ["amy", "beth", "sam"], ["dave", "sean", "peter"] ], "peter"));

edited Sep 4, 2018 at 13:24

answered Sep 4, 2018 at 12:03

user3297291

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2 Comments

hendryqiang Over a year ago

thanks for reply it don't work if my array were : filteredArray([ ["amy", "beth", "sam"], ["dave", "sean", "peter"] ], "peter")

user3297291 Over a year ago

I tried to explain what was happening so you could decide for yourself what the best fix would be. I added an example that includes a "copy-pastable" snippet, but I'd still advice you to implement it using the for loop first.

Dipak · Accepted Answer · 2018-09-04 12:56:44Z

0

function filteredArray(arr, elem) {
  var resultArray = arr.filter(function(item) {
    return item.indexOf(elem) == -1;
  });
  return resultArray[0]
}
console.log(
  filteredArray([["trumpets", 2], ["flutes", 4], ["saxophones", 2]], 2)
);
console.log(
  filteredArray([ ["amy", "beth", "sam"], ["dave", "sean", "peter"] ], "peter")
);

This code snippet will return the first item in the input array which is not matching with the given second param to the function. If we need all the items which are not matching, replace return resultArray[0] with return resultArray.

Consider a case where we are calling this function with following parameter,

filteredArray([["trumpets", 2], ["flutes", 4], ["saxophones", 5]], 2)

return resultArray[0] will give ["flutes", 4]

If we need all the items which are not matching we can do

return resultArray will give [["flutes", 4], ["saxophones", 5]]

edited Sep 4, 2018 at 12:56

answered Sep 4, 2018 at 12:27

Dipak

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4 Comments

Matt Over a year ago

What are you replacing resultArray[0] with? You have the same code as the replace...

Dipak Over a year ago

@Matt If there is more than one item in the input array which is not matching for the given elem value, resultArray will have multiple items in it. In that case, we can return the whole array instead of the first element.

Dipak Over a year ago

@Matt Updated my answer with that scenario as well

Matt Over a year ago

I get your scenario and I know what to replace it with, but OP may not. You say return resultArray[0] with return resultArray[0]. Make your changes in your text to display correctly.

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