确定奇数和偶数

Question

Can someone tell me what I am doing wrong here? What I am trying to do is looping through the list and assign a background colour for odd and even numbers.

Thanks in advance.

 var box = document.querySelectorAll('.links-wrapper li'); for(var i = 0; i < box.length; i++){ if(box[i] % 2 === 0){ box[i].style.backgroundColor = 'red'; } else { box[i].style.backgroundColor = 'blue'; } } 

Answer 1

Change box[i] to i

for(var i = 0; i < box.length; i++){
    if(i % 2 === 0){
        box[i].style.backgroundColor = 'red';
    } else {
        box[i].style.backgroundColor = 'blue';
    }
}

Else you can use css psuedo selector

 .links-wrapper li:nth-child(even) { color: red } .links-wrapper li:nth-child(odd) { color: green } 

 <ul class="links-wrapper"> <li> 1</li> <li> 2</li> <li> 3</li> <li> 4</li> <li> 5</li> </ul>