方法一

var arr1 = [1, 2, 3]
var arr2 = [1, 3]
var arr3 = arr1.filter(el => !arr2.includes(el))

includes 是 es 6 的，也可以用下面的，箭头函数es6的，不行你就转成普通函数：

var arr3 = arr1.filter(el => !~arr2.indexOf(el))

方法二

var m = {};
arr1.forEach(function(al){m[al]=al;})
arr2.forEach(function(bl){delete m[bl];})
console.dir(Object.keys(m))

方法三

var arr1 = ["", "100", "120", "125", "125", "130", "130"];
var arr2 = ["", "120", "125", "125", "130"];
var arr3 = [];
arr1.forEach((a)=>{
    let c = arr2.findIndex(b=>a == b);
    if (c > -1) delete arr2[c];
    else arr3.push(a);
});
console.log(arr3)  //["100", "130"]

方法四

var arr1 = ["", "120", "125", "125", "130", "130", "130", "130", "130"];

var arr2 = ["", "120", "125", "130"];

for (var i = arr1.length - 1; i >= 0; i--) {
    a = arr1[i];
    for (var j = arr2.length - 1; j >= 0; j--) {
        b = arr2[j];
        if (a == b) {
            arr1.splice(i, 1);
            arr2.splice(j, 1);
            break;
        }
    }
}

console.log(arr1);  // ["125","130","130","130","130"]