Using the logical operator && within an if statement

Question

Using the logical operator && within an if statement

As I iterate over an array, my goal is to execute the following:

for (var i = 0; i < array.length && !(array[i][1] == 0 && array[i][2] == 'foo'); i++) {

This means that if 'i' is less than the length of the array AND it's false that array[i][1] is 0 AND array[i][2] is 'foo', then carry out a series of actions.

The issue arises when this condition doesn't work as expected. It consistently returns false whenever array[i][2] is 'foo', regardless of whether or not array[i][1] equals 0.

Interestingly, altering the for statement to this format:

for (var i = 0; i < array.length; i++) {

... and adding this snippet at the beginning of the loop:

if (array[i][1] == 0 && array[i][2] == 'foo') continue;

... resolves the issue. It seems like there might be an error in the syntax when trying to express "IF TRUE AND !(CONDITION 1 && CONDITION 2)", but I'm unsure where I've gone wrong. Can you identify my mistake?

javascript arrays

Answer 1

Answer №1

In order to keep the loop running and move on to the next iteration when the test

!(array[i][1] == 0 && array[i][2] == 'foo')

fails, you should place the test inside the loop body and include the continue statement.

It is important to understand that if this test is placed in the loop control expression, the loop will simply stop when it fails. It will not skip the current iteration and proceed to the next one just as it would if i < array.length were false.

Answer 2

In order to keep the loop running and move on to the next iteration when the test

!(array[i][1] == 0 && array[i][2] == 'foo')

fails, you should place the test inside the loop body and include the continue statement.

It is important to understand that if this test is placed in the loop control expression, the loop will simply stop when it fails. It will not skip the current iteration and proceed to the next one just as it would if i < array.length were false.

Answer 3

Answer №2

Essentially, what I'm stating is that if the variable "i" is lower than the length of the array and it's not true that array[i][1] equals 0 and array[i][2] equals 'foo', then carry out a series of actions.

In JavaScript, this can be written as:

if((i < array.length) && !(array[i][1] == 0) && (array[i][2] == 'foo'))

If I incorporated this logic into your for loop, the if statement would look like this:

if(i < array.length && !(array[i][1] == 0 && array[i][2] == 'foo'))

It's important to note the position of the parentheses after the !. The revised for loop would appear as follows:

for (var i = 0; (i < array.length) && !(array[i][1] == 0) && (array[i][2] == 'foo'); i++) {

Answer 4

Essentially, what I'm stating is that if the variable "i" is lower than the length of the array and it's not true that array[i][1] equals 0 and array[i][2] equals 'foo', then carry out a series of actions.

In JavaScript, this can be written as:

if((i < array.length) && !(array[i][1] == 0) && (array[i][2] == 'foo'))

If I incorporated this logic into your for loop, the if statement would look like this:

if(i < array.length && !(array[i][1] == 0 && array[i][2] == 'foo'))

It's important to note the position of the parentheses after the !. The revised for loop would appear as follows:

for (var i = 0; (i < array.length) && !(array[i][1] == 0) && (array[i][2] == 'foo'); i++) {

Using the logical operator && within an if statement

Answer №1

Answer №2

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