从JSON文件加载数据的问题

Question

I am trying to load the content of a json file into an array. Instead of using the callback function to ensure file is loaded before I use it, I coded it like this:

var f_file_loaded = false;
var data = null;

$.getJSON('transformation.json', function(dt){
    f_file_loaded = true;
    data = dt;
});

while(!f_file_loaded){
    // Loop until file is loaded
}

console.log('data loaded', data);

This however, blocks the browser and the f_file_loaded doesn't seem to go true any time. What is the problem with my code?

Answer 1

while(!f_file_loaded){ doesn't work as you expect...it just creates an infinite loop.

You need to use the promise() interface.

$.when($.getJSON()).done(function() {
    // file is loaded, execute whatever code
});

Answer 2

That's because $.getJSON is an async call.

You should do something along these lines:

function data_loaded(data) {
    console.log('data loaded', data);
}

$.getJSON('transformation.json', function(dt){
    data_loaded(dt);
});

Answer 3

if you want to do sync not async call, then use this

your code above

$.ajax("transformation.json", {
dataType:'json',
async:false,
success:function(dt) {
data = dt;
}
});

your code below will continue execution after data is downloaded