how to create dynamic array with x y coordinates in react native

Question

Hello friends I want to create dynamic array of x-y coordinate with help of JSON array value so below JSON value

"data": [
  {
    "x_value": 1,
    "y_value": 1527116400
  },
  {
    "x_value": 43.45,
    "y_value": 1527030000
  },
  {
    "x_value": 43.95,
    "y_value": 1526943600
  },
  {
    "x_value": 43.95,
    "y_value": 1526857200
  },
  {
    "x_value": 44.05,
    "y_value": 1526598000
  },
  {
    "x_value": 44.25,
    "y_value": 1526511600
  },
  {
    "price": 44.1,
    "y_value": 1526425200
  },
  {
    "x_value": 44.3,
    "y_value": 1526338800
  },
  {
    "x_value": 44.25,
    "y_value": 1526252400
  }

]

My Js code as below

var data = null;
var array_data = response.sData.chart_data;
for (let index = 0; index < chart_data.length; index++) {
    data.push({ array_data[index].x_value, y: chart_data[index].y_value });
}

When I run above code I get error message like;

TypeError: null is not an object (evaluating 'data.push')

Any idea how can I solve this? Your all suggestions are appreciable.

You can't use Array.prototype.push() on a boolean variable — Yosvel Quintero
– Yosvel Quintero, Commented May 25, 2018 at 10:59

Yosvel Quintero · Accepted Answer · 2018-05-25 11:05:59Z

1

In your code you can't use Array.prototype.push() on a boolean var data = null; variable..

Better to use Array.prototype.map() that creates a new array with the results of calling a provided function on every element in the calling array.

Code example:

const chart_data = [{"x_value": 1,"y_value": 1527116400},{"x_value": 43.45,"y_value": 1527030000},{"x_value": 43.95,"y_value": 1526943600},{"x_value": 43.95,"y_value": 1526857200},{"x_value": 44.05,"y_value": 1526598000},{"x_value": 44.25,"y_value": 1526511600},{"price": 44.1,"y_value": 1526425200},{"x_value": 44.3,"y_value": 1526338800},{"x_value": 44.25,"y_value": 1526252400}];
const data = chart_data.map(coordinate => ({
  x: coordinate.x_value,
  y: coordinate.y_value
}));

console.log(data);

answered May 25, 2018 at 11:05

Yosvel Quintero

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