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//normal
var array = [1,2,3];
var sum1 = 0;
for(var i = 0 ;i < array.length ;i++) {
sum1 += array[i];
}
console.log(sum1);
// array.reduce
var sum2 = array.reduce(function (a,b) {
return a+b;
});
console.log(sum2);
// array.map
var sum3 = 0;
function getSum(item, index, array) {
sum3 += item;
}
array.map(getSum);
console.log(sum3);
// _.reduce
var sum4 = _.reduce(array, function(a, b){
return a + b;
});
console.log(sum4);
// _.reduceRight
var sum5 = _.reduceRight(array,function (a,b) {
return a+b;
});
console.log(sum5);
//邪恶的eval
var sum6 = eval(array.join("+"));
console.log(sum6);
//for in
var sum7 = 0;
for( var i in array ) {                                             
    sum7 += array[i]                     
}
console.log(sum7);