How to modify an object property given its location within the object

问题

Given an object obj, I can modify its properties by using something like obj.a.b.c = "new value". However, I want to be able to do this programmatically, with the property's location in the form of an array. How can I make a function that looks like this:

modifyProperty(obj, ["a", "b", "c"], "new value");

and is equivalent to

obj.a.b.c = "new value";

?

回答1:

You could use Array#reduce for it, with a default object if no object is available.

function modifyProperty(object, path, value) {
    var last = path.pop();
    path.reduce(function (r, a) {
        if (!(a in r)) {
            r[a] = {};
        }
        return r[a];
    }, object)[last] = value;
}

var object = {};
modifyProperty(object, ["a", "b", "c"], "new value");
console.log(object);

回答2:

You can do something like this:

function modifyProperty(obj, props, val) {
    var propName = props.pop();
    var o = props.reduce(function(obj, p) {
        return obj[p];
    }, obj);
    o[propName] = val;
}

var obj = {
   a: {b: {c: "old value"}}
}

modifyProperty(obj, ["a", "b", "c"], "new value");

console.log(obj);

回答3:

In order to set the object values dynamically i have a code called Object.prototype.setNestedValue() This will take an array of items which designate the properties of an array and the last one is the value. Such as

Object.prototype.setNestedValue = function(...a) {
  a.length > 2 ? typeof this[a[0]] === "object" && this[a[0]] !== null ? this[a[0]].setNestedValue(...a.slice(1))
                                                                       : (this[a[0]] = typeof a[1] === "string" ? {} : new Array(a[1]),
                                                                         this[a[0]].setNestedValue(...a.slice(1)))
               : this[a[0]] = a[1];
  return this;
};

var obj = {}.setNestedValue("a","b","c",100);
console.log(JSON.stringify(obj,null,2));

If instead of string arguments you use integers you get an array instead such as

Object.prototype.setNestedValue = function(...a) {
      a.length > 2 ? typeof this[a[0]] === "object" && this[a[0]] !== null ? this[a[0]].setNestedValue(...a.slice(1))
                                                                           : (this[a[0]] = typeof a[1] === "string" ? {} : new Array(a[1]),
                                                                             this[a[0]].setNestedValue(...a.slice(1)))
                   : this[a[0]] = a[1];
      return this;
    };

    var obj = {}.setNestedValue("a",2 ,3,100);
    console.log(JSON.stringify(obj,null,2));

来源：https://stackoverflow.com/questions/39300465/how-to-modify-an-object-property-given-its-location-within-the-object