Calling a function from data()

Question

I'm new to vue.js 2 . I'm currently recreating this graph inside with the vue framework : https://codepen.io/apexcharts/pen/rqWeBX

I need to get some datas from a generateDayWiseTimeSeries() function . I'm currently calling it from DATA() and it leads me to this error :

[Vue warn]: Error in data(): "ReferenceError: generateDayWiseTimeSeries is not defined"

I have tried out returning data with the .this syntax and placing the function inside of the created: part, with no luck.

This is my vue.js code, i would appreciate if you could tell me if that's the right way to do .

Vue.component("apexchart", VueApexCharts);

const Dashboard = {
  data: function() {
    return {
     series_5: [
        generateDayWiseTimeSeries(new Date("22 Apr 2017").getTime(), 115, {
          min: 30,
          max: 90
        })
      ]
    };
  },
  components: {
    apexcharts: VueApexCharts
  },
  methods: {
    generateDayWiseTimeSeries: function(baseval, count, yrange) {
      var i = 0;
      var series = [];
      while (i < count) {
        var x = baseval;
        var y =
          Math.floor(Math.random() * (yrange.max - yrange.min + 1)) +
          yrange.min;

        series.push([x, y]);
        baseval += 86400000;
        i++;
      }
      return series;
    }
    },
  ,
  template: `
    // THE TEMPLATE IS USELESS FOR THIS PROBLEM
   <div class="container">

        <div class="row" > 
            <div class="col-sm col-xs-12">
                    <div  class="card " style ="margin-bottom : 20px"  >

                        <div class="card-body">
                            <h5 class="card-title">Indices de ventes</h5>
                            <p class="card-text">Ventes totales .</p>
                            <div><apexchart  type="bar" :options="options_1" :series="series_1"></apexchart></div>
                        </div>
                    </div>
               </div>
                <div class="col-sm col-xs-12">

                                <div  class="card " style ="margin-bottom : 20px"  >

                        <div class="card-body">
                            <h5 class="card-title">Ventes</h5>
                            <p class="card-text">Indice des ventes total.</p>
                           <div><apexchart type="line" :options="options_2" :series="series_2"></apexchart></div>
                        </div>
                    </div>
                </div>



         </div> // THE TEMPLATE IS USELESS FOR THIS PROBLEM

`
};

EDIT : Modified

series_5: [
        this.generateDayWiseTimeSeries(new Date("22 Apr 2017").getTime(), 115, {
          min: 30,
          max: 90
        })
      ]

And now it seems to be working !

Answer 1

Your issue can be solved by adding this to your call to generateDayWiseTimeSeries().

series_5: [
  this.generateDayWiseTimeSeries(new Date("22 Apr 2017").getTime(), 115, { min: 30, max: 90 })
]

It is not declared as a global function, so you need to provide the context when calling it.

---

That being said, it seems like what you are looking for is a computed property. Modify your JavaScript as follows:

const Dashboard = {
  data: function() {
    return {};
  },
  components: {
    apexcharts: VueApexCharts
  },
  computed: {
    series_5() {
      return this.generateDayWiseTimeSeries(new Date("22 Apr 2017").getTime(), 115, { min: 30, max: 90 });
    }
  },
  methods: {
    generateDayWiseTimeSeries: function(baseval, count, yrange) {
      var i = 0;
      var series = [];
      while (i < count) {
        var x = baseval;
        var y =
          Math.floor(Math.random() * (yrange.max - yrange.min + 1)) +
          yrange.min;

        series.push([x, y]);
        baseval += 86400000;
        i++;
      }
      return series;
    }
    },
  ,

  ...

}

In general, logic doesn't belong in the data() function. By convention, data() just returns a JSON object that represents the Vue instance's data.