在下划线js中，我可以在输入where方法作为linq select投影后使用pluck方法获取多列吗

var people = [
    {firstName : "Thein", city : "ny", qty : 5},
    {firstName : "Michael", city : "ny", qty : 3},
    {firstName : "Bloom", city : "nj", qty : 10}
];

var results=_.pluck(_.where(people, {city : "ny"}), 'firstName');

例如：我需要firstName and qty.

要投影到多个属性，您需要map http://underscorejs.org/#map，不采摘：

var results = _.map(
    _.where(people, {city : "ny"}), 
    function(person) {
        return { firstName: person.firstName, qty: person.qty };
    }
);

[{"firstName":"Thein","qty":5},{"firstName":"Michael","qty":3}]

(Fiddle) http://jsfiddle.net/Wm8YC/1/

请注意，如果您愿意，您可以创建一个辅助方法“pluckMany”，它与带有变量参数的 pluck 执行相同的操作：

// first argument is the source array, followed by one or more property names
var pluckMany = function() {
    // get the property names to pluck
    var source = arguments[0];
    var propertiesToPluck = _.rest(arguments, 1);
    return _.map(source, function(item) {
        var obj = {};
        _.each(propertiesToPluck, function(property) {
            obj[property] = item[property]; 
        });
        return obj;
    });
};

您可以使用_.mixin http://underscorejs.org/#mixin函数添加一个“pluckMany”函数_命名空间。使用这个你可以简单地写：

var results = _.chain(people).where({city : "ny"}).pluckMany( "firstName", "qty").value();

(Fiddle) http://jsfiddle.net/Wm8YC/16/