Does a JavaScript If Statement with Multiple Conditions Test All of Them

Does a javascript if statement with multiple conditions test all of them?

The && operator "short-circuits" - that is, if the left condition is false, it doesn't bother evaluating the right one.

Similarly, the || operator short-circuits if the left condition is true.

EDIT: Though, you shouldn't worry about performance until you've benchmarked and determined that it's a problem. Premature micro-optimization is the bane of maintainability.

How to specify multiple conditions in an 'if' statement in JavaScript

Just add them within the main bracket of the if statement like:

if ((Type == 2 && PageCount == 0) || (Type == 2 && PageCount == '')) {
    PageCount = document.getElementById('<%=hfPageCount.ClientID %>').value;
}

Logically, this can be rewritten in a better way too! This has exactly the same meaning:

if (Type == 2 && (PageCount == 0 || PageCount == '')) {

multiple conditions in an if statement in javascript

You can use Array.includes to check if the current pathname exists in a given array.

let pathArr = ['/', '/kurikulum/', '/pengembangan-diri/', '/statistik/', '/teknologi/', '/ekonomi/', '/desain/', '/corona/'];
let testPath = '/desain/';

if (pathArr.includes(testPath)) {
   document.write('path found!');
};

javascript multiple OR conditions in IF statement

With an OR (||) operation, if any one of the conditions are true, the result is true.

I think you want an AND (&&) operation here.

Checking multiple conditions in JavaScript with only if/else statements

the

...&& (num4 < 9 && num4 > 20)

will be false always,

maybe you mean:

...&& (num4 < 9 || num4 > 20)

In JavaScript, does an if with multiple or's evaluate all statements before continuing?

You're right. It's called short circuit evaluation, and it applies to both || and &&.

For ||, evaluation of the right hand side takes place only if the left hand side evaluates to false.

For &&, evaluation of the right hand side takes place only if the left hand side evaluates to true.

Note that it's not just for performance. It also prevents errors from occurring: sometimes evaluating the right hand side would be unsafe or meaningless if the left hand side were not as expected.

How to specify multiple conditions in an array and call it in an if statement in javascript

Don't enclose the boolean values in backticks, as that makes them strings.

const addition = (...numbers) => {

let arrayOfTest = [
    numbers.length === 0,
    numbers.some(isNaN),
    numbers === null,
];
if (arrayOfTest.includes(true)) {
    throw new Error("Invalid Input");
} else {
    return numbers.reduce((a, b) => {
        return a + b;
    });
}
};

What condition is false in a multiple conditions if statement

Since the conditions are mutually exclusive, you can just use an else if without nesting.

if (condition1 && condition2 && condition3) {
    doSomething();
} else if (!condition1) {
    doWhatIDoWhenC1isFalse();
}
// add more else-if conditions as needed

If only one of your conditions can be false at a time (or if you don't care when two of them are false) then you can just have three else-if clauses and check each condition individually. If you do need to treat the cases where two conditions are false separately, you'll need an else-if for each combination. Pay close attention to the order you list them in if that's the case. The cases where you check if two conditions are both false should come before the cases where you only check one condition.

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