Call JavaScript Constructor using an array for the arguments

Question

I have a constructor function in JavaScript as below and want to supply constructor arguments from an array:

 function dataRow(value1, value2, value3, value4, value5) {
                this.val1 = value1;
                this.val2 = value2;
                this.val3= value3;
                this.val4 = value4;               
                this.val5 = value5;
}

Now I want the constructor arguments supplied from an array:

var dataArray = new Array();

dataArray("Value1","Value2","Value3","Value4","Value5","Value6"...........) 

I want (value1, value2, value3, value4, value5) this part to filled from my dataArray.

Answer 1

In modern environments, you can use spread notation:

var row = new dataRow(...dataArray);

function dataRow(v1, v2, v3, v4, v5) {
  this.v1 = v1;
  this.v2 = v2;
  this.v3 = v3;
  this.v4 = v4;
  this.v5 = v5;
}

var dataArray = [1, 2, 3, 4, 5];
var row = new dataRow(...dataArray);
console.log(row.v1);
console.log(row.v2);
console.log(row.v3);
console.log(row.v4);
console.log(row.v5);

In older environments, it's a real pain to do this. In your specific case, probably just do it the hard way:

dataRow(dataArray[0], dataArray[1], dataArray[2], dataArray[3], dataArray[4]);

Or you can separate creation from the call, and call it with Function#apply:

var row = Object.create(dataRow.prototype);
dataRow.apply(row, dataArray);

function dataRow(v1, v2, v3, v4, v5) {
  this.v1 = v1;
  this.v2 = v2;
  this.v3 = v3;
  this.v4 = v4;
  this.v5 = v5;
}

var dataArray = [1, 2, 3, 4, 5];
var row = Object.create(dataRow.prototype);
dataRow.apply(row, dataArray);
console.log(row.v1);
console.log(row.v2);
console.log(row.v3);
console.log(row.v4);
console.log(row.v5);

That wouldn't work with a constructor created via class, but if you're creating it via class, use spread notation; they were introduced as the same time (ES2015).

---

I would suggest not doing this, though, especially in light of your comment below:

...how to create this dynamically this.val1 = value1; this.val2 = value2; this.val3= value3;...

Instead, use a single array property, and pass in an array which you either keep or copy:

function dataRow(values) {
  this.values = values;
  // or: this.values = values.slice();
  // to make a shallow copy
}

var dataArray = [1, 2, 3, 4, 5];
var row = new dataRow(dataArray);
console.log(row.values);