Get data from Fetch to apply if statement

I Beginner in JavaScript, I’m trying to apply an If to a value that I got through fetch but gave me this error “script.js:41 Uncaught (in promise) TypeError: Cannot read property ‘substr’ of undefined at datos (script.js:41)”. I need to store in a new array only the data in base a specific date. How can I take the data from fetch and don’t have to wait for the data to be load. I hope you can understand me.

const fecha = new Date();
const today = fecha.getDate();
const year = fecha.getFullYear();
const month = fecha.getMonth() + 1;
const date = `${month}/${today}/${year}`;

    .then(response => response.text()
        .then(data => {

            let info = new Array();
            info = datos(data);


//Function get Array data
async function datos(data) {

    let arrayLineas = new Array();
    let arrayColumnas = new Array();
    let arrayFiltered = new Array();

    let texto = data;
    arrayLineas = texto.split(/\n|\r/).splice(11);
    for (let i = 0; i < arrayLineas.length; i++) {
        arrayColumnas[i] = arrayLineas[i].split("^");


    for (let x = 0; x < arrayColumnas.length; x++) {
        let date_db = "";
        date_db = arrayColumnas[x][17];

//In this "If"  is where the error happened
        if (date === date_db.substr(0,10)) {



Submit an answer

This textbox defaults to using Markdown to format your answer.

You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!

Sign In or Sign Up to Answer

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

Want to learn more? Join the DigitalOcean Community!

Join our DigitalOcean community of over a million developers for free! Get help and share knowledge in Q&A, subscribe to topics of interest, and get courses and tools that will help you grow as a developer and scale your project or business.

Interesting achive, thanks for sharing