XMLHttpRequest send() from local file returns undefined with Workers

Question

I got a problem by handling with workers, when i make my request the XMLHttpRequest() send returns null, but the onload method returns the file which i expected when i call send. What am I doing wrong? Here's the code:

function pegarDados(){
    let requisicao = new XMLHttpRequest();
    requisicao.overrideMimeType('text/plain'); 
    requisicao.setRequestHeader('X-Requested-With', 'JSONHttpRequest');
    requisicao.open('GET','./assets/data/dados.json', false);
    requisicao.onload = function(){
        return JSON.parse(this.response);
    };  
    let resultado = requisicao.send();
    return resultado.responseText;   
}
self.onmessage = function (event) {
    if(event.data == 'lista'){
        let dados = pegarDados();
        console.error(dados);
        self.postMessage(dados);
    }
}

Answer 1

XMLHttpRequest.send()actually has a return value of undefined.

In your code, you are trying to assign the set the value of your request by doing:

let resultado = requisicao.send();

which would obviously assign undefined to the variable.

What you were doing with xhr.onload is what I would do too, I don't really see why you want to have two return methods.

Looking as you made your xhr not asynchronous, you could just do:

requisciao.send();
return requisciao.responseText;