json去重

Array.prototype.removerepeatattr = function () {
    var tmp = {}, b = [], a = this;
    for (var i = 0; i < a.length; i++) {
        if (!tmp[a[i].id]) {
            tmp[a[i].id] = !0;
        } else {
            a.splice(i, 1);
            
        }
    }
};

var a=[{"id":"1"}, {"id":"2"}, {"id":"3"}, {"id":"4"}, {"id":"1"}];
a.removerepeatattr();