Complex condition in FOR loop in JavaScript

Question

I was wondering if it's possible to state 2 statements as a FOR loop's condition in JavaScript.

for (var i = 0; i < x.length || 10; i++) {
}

instead of writing

for (var i = 0; i < x.length; i++) {
 if(i<10) {
 }
}

Used references (didn't help too much):

Multiple conditions in for loop

Multiple conditions in for statement

• Choxx: Visit this link w3schools.com/js/js_loop_for.asp
• Kiss Koppány: @choxx I know how FOR works, I was just wondering if it's possible to do it in the way I asked.
• Kiss Koppány: GUYS, the question wasnt about how a for loop works.. please keep in mind when downvoting.
• Choxx: Well then you must also know the code you wrote in Ist part doesn't make any sense..
• Choxx: You can't directly write i < x.length || 10; If you are assigning multiple conditions in FOR, then you must have to follow the coding rules as per standard. i < x.length || i < 10

Answer 1

If the goal is to end the loop when i reaches 10 or i reaches the end of the array, you may write it like this :

for (var i=0; i<x.length && i<10; i++) {

In that case you might also compose it like this

for (var i=0; i<Math.min(x.length,10); i++) {

or for better performances :

for (var i=0, n=Math.min(x.length,10); i<n; i++) {

• Kiss Koppány: isn't it possible in the simple way as I wrote it? like i < x.length || 10
• Denys Séguret: @KissKoppány no, this writing makes no sense
• Johannes Reuter: No it isnt possible this way
• 11684: @MoisheLipsker No, you'd need to use &&. Otherwise, if x.length is smaller than 10 you'll go out of bounds.
• Kiss Koppány: @dystroy your solution is nice and kind of what I was looking for: for (var i=0; i<Math.min(x.length,10); i++) { Nice and clear.

Answer 2

The problem is not in the syntax of the for loop but in the way you put the conditional stetement:

i < x.length || 10

evaluates as

(i < x.length) || 10

that evaluates as

true || 10

or

false || 10

depending on the value of i and the length of x

The first will then result in true while the latter in 10.

So the for loop goes on forever and is not equivalent to the second code snipped you posted.

The above is to explain why the two code snippets you posted are not functionally equivalent.

The correct statement is

for (var i=0; i<x.length && i<10; i++) {

or one of the other proposed in dystroy's excellent answer.