Sum of numerous arguments

Sum of numerous arguments

// 1/4/2016
// Sum of numerous arguments

// After calling the function findSum() with any number of non-negative integer 
// arguments, it should return the sum of all those arguments. If no arguments 
// are given, the function should return 0, if negative arguments are given, it 
// should return -1.

// eg
// findSum(1,2,3,4); // returns 10 
// findSum(1,-2);    // returns -1 
// findSum();        // returns 0

// Hint: research the arguments object on google or read Chapter 4 from 
// Eloquent Javascript

// Test.assertEquals(findSum(1,3,5), 9, "1 + 3 + 5 = 9")
// Test.assertEquals(findSum(0,3,9,2), 14, "0+3+9+2 = 14")
// Test.assertEquals(findSum(), 0, "If no arguments, function should return 0")
// Test.assertEquals(findSum(1,-2,4) , -1, "If negative arguments are passed, 
// function should return -1")
// Test.assertEquals(findSum(0), 0, "The sum of 0 is 0")

function findSum(){
    var total = 0;
    
    var arr1=Array.prototype.slice.call(arguments)
    
    if (arr1.length===0){
        return 0;
    }
    
    
    for(var i=0; i<arr1.length; i++){
         if(arr1[i]<0){
            return -1
        }
        if(typeof(arr1[i])==="number"){
            total+=arr1[i]
        }
        else{
            return false;
        }
    }
    return total;
}

findSum(1,-2,4)