Javascript beyond property accessors

问题

I read a lot about JS accessors here and figure out this gonna be good for me:

This is what I used for local fields:

TYPE_DEFAULT_VALUE= {
    number: 0,
    string: "",
    array: [],
    object: {},
};

typeOf = function (object) {
    if (typeof object === "number" && isNaN(object))
        return NaN;
    try {
        return Object.prototype.toString.call(object).slice(8, -1).toLowerCase();
    }
    catch(ex) {
        return "N/A";
    };
};

getAccessor = function(obj, key, type, defaultValue) {
    if (defaultValue === undefined) 
        defaultValue =  TYPE_DEFAULT_VALUE[type] === undefined ? null : TYPE_DEFAULT_VALUE[type];
    return {
        enumerable: true,
        configurable: true,
        get: function () {
            if (obj[key] === undefined) 
                obj[key] = defaultValue;
            return obj[key];
        },
        set: function (value) {
            if (typeOf(value) === type)
                obj[key] = value;
        },
    };
}

LocalFields = function (fields, object) {
    /**
    * field properties
    * { 
    *   type: [ required ] ( number | string | array | object | ... ),
    *   defaultValue: [ optional ]
    * }
    */
    if (! fields)
        throw "Too few parameters ...";
    if (! object) 
        object = this;

    var obj = this;
    var fieldsAccessor = {};
    for(key in fields){
        field = fields[key];
        fieldHandler = key[0].toUpperCase() + key.substr(1);
        if(! field.type)
            throw "Type not set for field: " + key;

        fieldsAccessor[fieldHandler] = getAccessor(obj, fieldHandler, field.type, field.defaultValue)
    }
    Object.defineProperties(object, fieldsAccessor);
}

Now for each Class I can just call something like:

Person = function(){
    new LocalFields({
        id:     { type: "number" },
        name:   { type: "string" },
        phone:  { type: "array" },
    }, this);
}

And then like VS getter and setter you'll call:

var alex = new Person();
alex.Name = "Alex Ramsi";
console.clear();
console.info(alex.Name);

this works for all types but there is a problem because getter and setter is the basic operation and what if I want to add an array field and call this append method or even prepend is there anyhow anyway to do that? For example How can I call:

        alex.Phone.append('+1234567890');

回答1:

That's a good effort but you forgot that there is no append function for array list! You can use push and any other array functionality. Check it again;

来源：https://stackoverflow.com/questions/30274789/javascript-beyond-property-accessors

标签

javascript

arrays

json

accessor