使用的var获取数组的最后一个元素

Question

i switch to using :

for (var element of elements)

instead of :

for (var i in elements)

Why? Because i was creating array prototypes and when i use var i in , the prototypes are considered as an element of that array.

My question is can i know if my element is the last element of that array, do i need to create another variable and do increment everytime till that variable is equal to elements.lentgh - 1 ?

Answer 1

You can do this by doing something like:

for (var element of elements){
    if(element === elements[elements.length-1]){
         // Last element being processed here
    }
}

It may be better to use Array.prototype.forEach based on your usecase

elements.forEach(function(element, index, array){
     if(index === elements.length-1){
         // Last element
     }
})

Answer 2

 var elements = ["a", "b", "c", "d"]; var i, len, text; for ( i = 0, len = elements.length, text = ""; i < len; i++) { text = elements[i] + ""; if(text === elements[elements.length-1]){ console.log('last', text); } } var elements = [5, 15, 78, 20,43,77]; var i, len, text; for ( i = 0, len = elements.length, text = 0; i < len; i++) { text = elements[i] ; if(text === elements[elements.length-1]){ console.log('last', text); } }