Question 108484 in Javascript Question posted in
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Woring with nested arrays in Javascript

I have the following code. I need to print only any Nested Arrays.

let newArray = ["Ameen", "John", ["Working", "Studying"], [10, 100, 30, 40]];

for (let i = 0; i < newArray.length; i++) {

*// `Nested For Loop To Print The Nested Arrays`*

  for (let j = 0; j <= i; j++) {
    if (Array.isArray(newArray[i])) {
      console.log(`Nested Array ${newArray[i][j]}`);
    }
  }
}
console.log(`Whole Array: ${newArray}`);

It’s working fine, however, the problem here is that the nested loop "j" prints "undefined" after the last element of the first nested array ["Working", "Studying"].

I understand that because the index of "i" is increased to "2", while the first nested array ["Working", "Studying"] only has 2 elements which mean two indexes (0,1). Thus, the "j" can’t find the element with an index of "2" within the first nested array.

The question is, how to make the nested loop "j" to not print "undefined" elements caused by the parent for loop index "i"?

Tags:

4

Answers


  1. Chosen as BEST ANSWER
    0

    After I squeezed my mind. I found the solution by adding another condition. Which is If the newArray[i] is an Array and If (this is the added condition) newArray[i][j] !== undefined as the following

    for (let i = 0; i < newArray.length; i++) {
  for (let j = 0; j <= i; j++) {
    if (Array.isArray(newArray[i]) && newArray[i][j] !== undefined) {
      console.log(`Nested Array ${newArray[i][j]}`);
    }
  }
}

    It's working as I wanted. However, I'm wondering if there is another way to achieve that. I appreciate your cooperation.


  2. 0

    I think the could be simplified by doing the following

    const nestedArrayItems = newArray.filter(item => Array.isArray(item)).flat()
nestedArrayItems.forEach(nestedArrayItem => console.log(nestedArrayItem))
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  3. 0

    A solution that came to mind immediately that would prevent unnecessarily looping a second time would be:

        for (let i = 0; i < newArray.length; ++i) {
        if(Array.isArray(newArray[i])) {
            for (let j = 0; j < newArray[i].length; ++j) {
                if (newArray[i][j] != undefined) {
                    console.log(`Nested Array ${newArray[i][j]}`);
                }
            }
        }
    }
    console.log(`Whole Array: ${newArray}`);
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  4. 0

    Here are the nested sub arrays:

    const
    newArray = ["Ameen", "John", ["Working", "Studying"], [10, 100, 30, 40]];
    
    newArray   //PRINT only nested sub arrays
      .forEach(a => {
          if( Array.isArray(a) ) {
              console.log( a );
          }
      });

    All the elements of the nested sub arrays:

    const
    newArray = ["Ameen", "John", ["Working", "Studying"], [10, 100, 30, 40]],
    
    nested = newArray   
      .reduce(
          (acc, curr) => [...acc, ...(Array.isArray(curr) ? curr : [])], []
      );
      
console.log( nested );
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