这是我个人的重学前端基础系列：

使用js闭包的函数式编程：

// outer/global scope: RED(1)

function lookupStudent(studentID) {
    // function scope: BLUE(2)

    var students = [
        { id: 14, name: "Kyle" },
        { id: 73, name: "Suzy" },
        { id: 112, name: "Frank" },
        { id: 6, name: "Sarah" }
    ];

    return function greetStudent(greeting){
        // function scope: GREEN(3)

        var student = students.find(
            student => student.id == studentID
        );

        return `${ greeting }, ${ student.name }!`;
    };
}

var chosenStudents = [
    lookupStudent(6),
    lookupStudent(112)
];

// accessing the function's name:
chosenStudents[0].name;
// greetStudent

chosenStudents[0]("Hello");
// Hello, Sarah!

chosenStudents[1]("Howdy");
// Howdy, Frank!