I'm new to learning JavaScript and I'm wondering how I can receive a single alert using only the if operator

Question

I'm new to learning JavaScript and I'm wondering how I can receive a single alert using only the if operator

Extracted from the book "Beginning JS 4th edition", this code snippet displays two alert messages when loaded in a browser due to two NaN entries in an array. To ensure that only one alert is shown every time, how can I achieve this using the if operator?

if (isNaN(degFahren[loopCounter]))
{ 
alert ("You have entered text parameters which will be skipped");
continue;
}

I am aware that the loop should execute only once within the @if block, but I am having trouble implementing it.

Appreciate your help!

javascript loops if-statement alerts

Answer 1

Answer №1

Utilize the appropriate array method known as includes to determine if a specific element is present in an array.

const arr = [1, NaN, NaN, 4];
if(arr.includes(NaN)) {
  alert('There are elements that will be skipped.');
}

Avoid using nested for loops unnecessarily.

If you want to find out the number of times a certain element appears in an array, consider using .filter to create a new array containing only the matching elements and then check the length of this new array:

const arr = [1, NaN, NaN, 4];
const NaNs = arr.filter(item => isNaN(item));
if(NaNs.length > 0) {
  alert('There are elements that will be skipped: ' + NaNs.length);
}

Answer 2

Utilize the appropriate array method known as includes to determine if a specific element is present in an array.

const arr = [1, NaN, NaN, 4];
if(arr.includes(NaN)) {
  alert('There are elements that will be skipped.');
}

Avoid using nested for loops unnecessarily.

If you want to find out the number of times a certain element appears in an array, consider using .filter to create a new array containing only the matching elements and then check the length of this new array:

const arr = [1, NaN, NaN, 4];
const NaNs = arr.filter(item => isNaN(item));
if(NaNs.length > 0) {
  alert('There are elements that will be skipped: ' + NaNs.length);
}

Answer 3

Answer №2

One way to tackle this issue is by implementing a variable:

let warningCount = 0;

Update and check its count every time an alert needs to be displayed:

if (warningCount++ == 0) alert("This message will only appear if it was the first one.");

Answer 4

One way to tackle this issue is by implementing a variable:

let warningCount = 0;

Update and check its count every time an alert needs to be displayed:

if (warningCount++ == 0) alert("This message will only appear if it was the first one.");

I'm new to learning JavaScript and I'm wondering how I can receive a single alert using only the if operator

Answer №1

Answer №2

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