如何在for循环上设置多个限制：javascript

Question

I am working with javascript arrays, here i am using for loop to get the top three results.(no .length limit)

Attempting to have something like

for(let a=0;a<usss.length || a<3;a++)

Simple

var users = ['s','g','h','i'];
for(let a=0;a<3;a++){//dont want to use a < users.length
   console.log(users[a]);
}

problem

var users2 = ['s','g'];
for(let a=0;a<3;a++){
  console.log(users2[a]);
}

The way around,

var users2 = ['s','g'];
for(let a=0;a<users2.length;a++){
 if(a<3){
  console.log(users2[a]);
 }
}

Real Question

How can i avoid using extra if() condition in my last stated code?

I am sorry if its very basic question, i just stuck on it. Any help or information will be appreciated. Thanks for your time.

Answer 1

This seems to work :

 var users = ['s','g','h','i']; var users2 = ['s','g']; for(let a=0;(a<3 && a<users.length) ;a++){ console.log(users[a]); } for(let a=0;(a<3 && a<users2.length);a++){ console.log(users2[a]); } 

Answer 2

There will be no way without using an if somewhere as you have to check the length of the value.

 var users = ['s','g','h','i']; // define the length value outside var length = users.length >= 3 ? 3 : users.length; for(let a=0; a < length; a++){ console.log(users[a]); } var users2 = ['s','g']; for(let a=0; a < length; a++){ console.log(users[a]); } // you can define it inside the for loop but it's not so nice for reading for(let a=0; a < (users.length >= 3 ? 3 : users.length); a++){ console.log(users[a]); } 

Maybe the nicest would be to create a function and pass the 3 as a maxLength parameter

 var logMax = function(users, maxLength, info) { let length = users.length >= maxLength ? maxLength : users.length; for(let a=0; a < length; a++){ console.log(info, ' => ' + users[a]); } } var users = ['s','g','h','i']; logMax(users, 3, 'first'); logMax(['s','g'], 3, 'second'); 

Answer 3

You could use also use Array.some()

Note: Check browser compatibility and/or use polyfill

 [1, 2, 3, 4, 5, 6, 7].some((el, idx) => { console.log(el); return ++idx === 4; /* <-- return top 4 */ }); 

Answer 4

Its very simple, I think you just need to go through the length of the array.

 var users2 = ['s','g'];
for(let a=0;a<users2.length;a++){
  console.log(users2[a]);
}