无法理解为什么我的JS无法正常工作

Question

Nothing is happening for me when I run this code.

var myarray = [2,2,2];

for ( var i = 0 ; i < myarray.length ; i++ ) {
  total = total + myarray[i];
}
alert("The total is " + total);

Answer 1

Try defining total outside of the loop first.

var myarray = [2, 2, 2];
var total = 0;
for (var i = 0; i < myarray.length; i++) {
  total += myarray[i];
}
alert(`The total is ${total}!`);

Something was happening, but you likely couldn't see it. Try to open the developer console in your browser if you're using one to run this, you'll see the error being generated.

Answer 2

Just declare your variable and initialise it:

var total =0;
for ( var i = 0 ; i < myarray.length ; i++ ) {
  total = total + myarray[i];
}
alert("The total is " + total);

Answer 3

A nice way to solve it is using reduce as below, cheers! ;)

 var arr = [1, 2, 3]; var total = arr.reduce((acum, current) => acum + current); console.log(total);