Question 50780 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript For Loop with If statement and Array

I want the array to start printing from the second element of the Array [2…].. but there is something I couldn’t understand. I wrote an if statement to achieve that, as shown below. However, it doesn’t return the wanted result. I mean, It starts printing from the beginning of the Array!!

let start = 0;
let mix = [1, 2, 3, "A", "B", "C", 4];

for (let i = start; i < mix.length; i++) {
  if (mix[i] === start) {
    continue;
  }
  document.write(`${mix[i]} <br>`);
}

But, when I replace the "mix[i]" with only "i" as shown below, it returns the wanted result and starts printing from the second element.

let start = 0;
let mix = [1, 2, 3, "A", "B", "C", 4];

for (let i = start; i < mix.length; i++) {
  if (i === start) {
    continue;
  }
  document.write(`${mix[i]} <br>`);
}

Updated: Thus, the question is what the difference between the first if and the second if, and why the first if "mix[i]" doesn’t print the wanted result while the second one it works!!

I appreciate your help.

Tags:

2

Answers


  1. 0

    mix[i] === start

    here mix[0] === 1 that’s why if block gets skipped, because start=0; and i is also 0 that’s why it’s the correct output in second example.

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  2. 0

    You are using the array value in that position for the first example and the index on the second example.
    For the first code your conditional is:

    if (mix[i] === start)

    In this case, mix[i] will be the value stored in that index, so for the first iteration it will be mix[0], that will be 1 in your array. 1≠0 so it won’t go to the continue and therefore print it.

    In your second code, the conditional is:

    if (i === start)

    In this case you are actually using the index position, not the array value for that index. That’s the difference.

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