How can data be shared across different JavaScript functions?

Question

How can data be shared across different JavaScript functions?

I have two dropdown lists where I'm trying to pass the selected values for both to another function. I know that the way I am currently doing it is not correct, but I have been staring at this code for so long that I can't seem to find the probably simple solution.

  d3.select("#parameterType").on("change", function() 
    {
        var selectedParameter = this.value;
        console.log(selectedParameter);
        filterData(selectedParameter);
    });


    d3.select("#dateTimeTaken").on("change", function() 
    {   
        var selectedMonth = this.value;
        console.log(selectedMonth);
        filterData(selectedParameter, selectedMonth)
    });


    function filterData(selectedParameter, selectedMonth)
    {
        console.log(selectedParameter);
        console.log(selectedMonth);
    }

Can someone please help guide me in the right direction?

javascript

Answer 1

Answer №1

To improve the functionality of your code, consider retrieving the chosen values within the function that is receiving the parameters. Here's an example:

function fetchSelectedData() {
   var selectedParam = document.getElementById("parameterType").value;
   var selectedMonth = document.getElementById("dateTimeTaken").value;
   console.log(selectedParam);
   console.log(selectedMonth);
}

Make sure to invoke this function whenever either of the selected values changes.

d3.select("#parameterType").on("change", function() { fetchSelectedData(); });

d3.select("#dateTimeTaken").on("change", function() { fetchSelectedData(); });

Answer 2

To improve the functionality of your code, consider retrieving the chosen values within the function that is receiving the parameters. Here's an example:

function fetchSelectedData() {
   var selectedParam = document.getElementById("parameterType").value;
   var selectedMonth = document.getElementById("dateTimeTaken").value;
   console.log(selectedParam);
   console.log(selectedMonth);
}

Make sure to invoke this function whenever either of the selected values changes.

d3.select("#parameterType").on("change", function() { fetchSelectedData(); });

d3.select("#dateTimeTaken").on("change", function() { fetchSelectedData(); });

Answer 3

Answer №2

Give this method a try:

To implement this solution, maintain the values of selectedParameter and selectedMonth outside of the function. When the user makes selections in the onchange event handlers, update the respective variable and then invoke the filterData function without any arguments. The filterData function will then verify if both variables are defined and take appropriate action based on that.

Here is the code snippet:

var filterData = (function () {
    var selectedParameter, selectedMonth;
    d3.select("#parameterType").on("change", function() 
    {
        selectedParameter = this.value;
        filterData();
    });

    d3.select("#dateTimeTaken").on("change", function() 
    {   
        selectedMonth = this.value;
        filterData();
    });

    function filterData()
    {
        if (selectedParameter === undefined || selectedMonth === undefined) {
            console.log("Both variables are not yet set.");
            return;
        }
        console.log("Both variables have been set!");
    }
    return filterData;
})();

I enclosed it within a closure to prevent variable leakage into the global scope and ensured that the closure returns the filterData function for wider accessibility beyond the closure itself.

Answer 4

Give this method a try:

To implement this solution, maintain the values of selectedParameter and selectedMonth outside of the function. When the user makes selections in the onchange event handlers, update the respective variable and then invoke the filterData function without any arguments. The filterData function will then verify if both variables are defined and take appropriate action based on that.

Here is the code snippet:

var filterData = (function () {
    var selectedParameter, selectedMonth;
    d3.select("#parameterType").on("change", function() 
    {
        selectedParameter = this.value;
        filterData();
    });

    d3.select("#dateTimeTaken").on("change", function() 
    {   
        selectedMonth = this.value;
        filterData();
    });

    function filterData()
    {
        if (selectedParameter === undefined || selectedMonth === undefined) {
            console.log("Both variables are not yet set.");
            return;
        }
        console.log("Both variables have been set!");
    }
    return filterData;
})();

I enclosed it within a closure to prevent variable leakage into the global scope and ensured that the closure returns the filterData function for wider accessibility beyond the closure itself.

Answer 5

Answer №3

To create a global variable, simply update the code from var selectedParameter = this.value; to just selectedParameter = this.value; without using the var keyword.

Answer 6

To create a global variable, simply update the code from var selectedParameter = this.value; to just selectedParameter = this.value; without using the var keyword.

How can data be shared across different JavaScript functions?

Answer №1

Answer №2

Answer №3

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