比较两个数组，无法使其返回true

Question

My objective is to compare the two arrays. I can't get it return false, it just compares the first values and returns. Am I not asking it correctly to loop through all values before determining true or false?

var array1 =[1,2,3];
var array2=[1,2,4];

var areArraysSame = function(array1, array2) {
   if(array1.length !== array2.length) {
       return "These are not the same length";
   }
   for(var i = 0; i <= array1.length; i++) {
      if(array1[i] !== array2[i]) {
      return "These are not the same array";

      }else{
      return "these are the same array";
      }
     }
    };
   console.log(areArraysSame(array1, array2));

Answer 1

You are not waiting for all comparisons to take place before returning true ( or your true string )

You should do this:

for(var i = 0; i <= array1.length; i++) {
    if(array1[i] !== array2[i]) {
        return false;
    }
}
return true;

Wait for the loop to end before returning true

Answer 2

You are returning immediately after checking the first value, remove the else block in the for loop such that it compares all the values as shown below :

var array1 =[1,2,3];
var array2=[1,2,4];

var areArraysSame = function(array1, array2) {
 if(array1.length !== array2.length) {
   return "These are not the same length";
 }
for(var i = 0; i <= array1.length; i++) {
  if(array1[i] !== array2[i]) {
   return "These are not the same array";
  }
 }
 return "These are the same array";
};
console.log(areArraysSame(array1, array2));

Answer 3

Return will stop your loop and exit the function. So since in the above code your first element for both arrays is 1 the code returns on the first iteration of the loop. If you want to return whether or not the arrays match return after the loop and use a boolean variable to keep track of whether or not the arrays match. Only return in the loop on a false statement.

Answer 4

You have a return statement in the first iteration of your for loop; after the first item in each array is compared your loop will end whether it's true or false.

You can store a condition and base your return on that.

    var array1 = [1, 2, 3];
    var array2 = [1, 2, 4];

    var areArraysSame = function (array1, array2) {
        var isSame = true;

        if (array1.length !== array2.length) {
            return "These are not the same length";
        }

        for (var i = 0; i <= array1.length; i++) {
            if (array1[i] !== array2[i]) {
                isSame = false;
            }
        }
        return isSame ? "These are the same array" : "These are not the same array";
    };

    console.log(areArraysSame(array1, array2));