合并两个数组的js函数

function unionArray(arrayA, arrayB) {
    for (var i = 0; i < arrayA.length; ++i) {
        var inArrID = false;
        for (var j = 0; j < arrayB.length; ++j) {
            if (arrayB[j] == arrayA[i]) {
                inArrID = true;
                break;
            }
        }
        
        if (!inArrID) {
            arrayB.push(arrayA[i]);
        }
    }
    
    var result = arrayB.join(',');
    result = result.replace(/^,/, '').replace(/,$/, '');
    return result;
}