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Sometimes, we need to perform different actions based on different conditions.… To do that, we can use the if statement and the conditional operator ?… It executes when the condition is falsy.… Conditional operator ‘?’.Sometimes, we need to assign a variable depending on a condition.… can return a value that depends on more than one condition.

Any expression or variable can be a loop condition, not just comparisons: the condition is evaluated… condition i < 3 Checked before every loop iteration. If false, the loop stops.… body alert(i) Runs again and again while the condition is truthy.… Breaking the loop.Normally, a loop exits when its condition becomes falsy.… – The condition is checked after each iteration. for (;;) – The condition is checked before each iteration

Most of the time, OR || is used in an if statement to test if any of the given conditions… We can pass more conditions… Sometimes, people use this feature to execute commands only if the condition on the left part is falsy

In other words, they do not match a character, but rather force the regexp engine to check the condition

Unlike the anchors ^ $, that only test the condition (start/end of a line), \n is a character, so it

Here we can rewrite the same using the conditional operator ?… The condition n == 1 is falsy, so the flow continues into the second branch of if:… The exit.During the execution of pow(2, 1), unlike before, the condition n == 1 is truthy, so the first… rewrite is non-trivial, especially when a function uses different recursive subcalls depending on conditions

A single-line construct, such as if (condition… For example, instead of adding a nested if conditional like this:

It happens in logical operations (later we’ll meet condition tests and other similar things) but can

On the last line there is a conditional

Conditional breakpoints Right click on the line number allows to create a conditional breakpoint

Lookahead allows to add a condition for “what follows”. Lookbehind is similar, but it looks behind.

It matches elements based on two conditions: That’s a slotted element, that comes from the light DOM

Conditional The only operator with three parameters: cond ? resultA : resultB.

difficult to manage, especially if we have real code instead of ... that may include more loops, conditional

A request is safe if it satisfies two conditions: Safe method: GET, POST or HEAD Safe headers – the… “Safe” requests must satisfy the following conditions: Method: GET, POST or HEAD.

The obvious solution would be to check the value using if or the conditional operator ?

A samesite=lax cookie is sent if both of these conditions are true: The HTTP method is “safe” (e.g.… E.g. opening a website link from notes that satisfy these conditions.

…But if a Function Declaration does not suit us for some reason, or we need a conditional declaration

with the response (if the response headers permit this action), "no-cache" – create a conditional

want to get all returning values, but it can be useful when we want to stop generator in a specific condition

A conditional import, like this, won’t work:

useful for advanced programming patterns when we use functions to generate classes depending on many conditions

Bezier curve.The timing function can be set as a Bezier curve with 4 control points that satisfy the conditions

How do we find an object with a specific condition? Here the arr.find(fn) method comes in handy.

Object.keys/values/entries Invariants JavaScript enforces some invariants – conditions