Navigating a JSON object in d3 after it has been loaded

After loading a JSON object using d3.json and assigning it to a global variable, I encountered an issue where the console returned 'undefined' when printing the global variable. However, typing the global variable in the Chrome console returned the expected result. Essentially, my goal is to load the JSON object and use it outside of the d3.json function. While this may seem like a simple task, I am still new to JavaScript and d3, so any assistance would be greatly appreciated!

Thank you!

Below is the provided code snippet:

<script type = "text/javascript" source='https://d3js.org/d3.v4.min.js'>

var gapminder;

d3.json("D3_jsondata.json", function(data){
  gapminder = data;
});
// The above prints in the console when 'gapminder' is typed

console.log(gapminder); // Prints as 'undefined' in Chrome's console
</script>

Answer №1

When you invoke .json(), a promise is returned for the content of the http response that has not been fully loaded yet. To ensure timely rendering, consider initiating the rendering process within the callback function of the json request!

Answer №2

When using d3.json, d3.csv, and d3.tsv for asynchronous requests, the console.log() function will execute before the d3.json() function, leaving "gapminder" as undefined.

Once the console.log() has run, the d3.json() function will execute and assign the json data to "gapminder", thereby removing its status of being undefined.

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