local vs global variable in Javascript

Question

I have this code in Javascript:

var words = [];

d3.json("myFile.json", function(data) {
    words = data.words;
    console.log(words);  //Log output to console
});

console.log(words);  //Log output to console

The first console.log(words); shows an array of seven objects. But the second console.log(words); shows an empty array. So it looks like words outside of the d3.json function is not the same as words inside that function.

I also have tried to use console.log(window.words); outside of the function and it still shows an empty array.

How can I get the data that I have read from myFile.json in the d3.json function, outside of that function?

Lars Kotthoff · Accepted Answer · 2014-04-20 22:45:29Z

3

d3.json is an asynchronous function. That means that the code you pass is not executed immediately, but as a callback after the request for the JSON file returns. That is, a network request is sent for the file, but the normal flow of execution continues.

The console.log(words); outside d3.json is simply executed before the call returns and the array is populated.

answered Apr 20, 2014 at 22:45

Lars Kotthoff

109k16 gold badges210 silver badges210 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

TJ1 Over a year ago

Thanks for the answer. Is there a way I can wait until the array populated and then use it?

TJ1 Over a year ago

I tried to delay the second console.log(words); by adding: var aa; for (var i = 0; i < 100000; i++) { aa= 10 + Math.random() * 90; } before that but it didn't help!

user1614080 Over a year ago

You can use queue, move you code into d3.json call or call a function and pass words to from inside the d3.json function. In addition to Lars comments this question might also help.

TJ1 Over a year ago

@user1614080 thanks for the comment, I did that and it worked, i.e I moved my code inside d3.json function.

Collectives™ on Stack Overflow

local vs global variable in Javascript

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related