How to check for a nearby target in Javascript?

Question

I made a function called CheckForTarget() to check the closest target to an object. I used the p5.jsfunction dist() to calculate the distance but the answer to this calculation results as NaN.

checkForTarget() {
    let closest;
    let index = 0;

    for (let i = 0; i < food_amount; i++) {
        let d = dist(this.x, this.y, food[i].pos.x, food[i].pos.y);
        console.log(d);
        if (d < this.sense && d < closest) {
            closest = d;
            index = i;
        }

    }

}

Expected result: a certain distance between 0 and the radius

Actual result: NaN

Added:

class Dot {
    constructor() {
        this.pos = createVector(width / 2, height / 2);
        this.vel = createVector();
        this.acc = createVector();