在JavaScript上将整数添加到数组

Question

I'm developing an application that is supposed to draw some rectangles on a canvas. The idea is draw them by putting each one at the last's side - I mean, start drawing it where the other finishes.

I have created a button that takes the values from an input, that was the easy part. I add this values to an Array, but each time I push the button, the array is empty again. I've heard that I need an 'instance variable', but I'm quite lost right now.

Any help will be welcome. this is the code

function corta() {
    var c = document.getElementById("myCanvas");
    var ctx = c.getContext("2d");
    var medida1 = document.getElementById('medida2').value;
    var medida2 = document.getElementById('medida1').value;
    var corte1 = Math.round(medida1);
    var corte2 = Math.round(medida2);
    var arrayAncho = [];
    var arrayLargo = [];
    var ancho = 0;
    var largo = 0;
    arrayLargo.push(medida2);
    arrayAncho.push(medida1);
    //ancho, largo

    document.getElementById('medida2').onclick = function () { this.value = ''; };
    document.getElementById('medida1').onclick = function () { this.value = ''; };

    //metodo para el ancho

    for (var i = 0; i < arrayAncho.length ; i++) {
        ancho += arrayAncho[i];
    }

    if (arrayAncho.length == 1) {
        ctx.fillStyle = "#58FA58";
        ctx.fillRect(0, largo, corte1, corte2);
    } else
    if (medida1 > 122 - ancho) {
        ctx.fillStyle = "#58FA58";
        ctx.fillRect(ancho, largo, corte1, corte2);//ancho, largo
    }

    medida1 = 0;
    medida2 = 0; 
}

Answer 1

Every time you run the function you run

var arrayAncho = [];
var arrayLargo = [];

This makes them blank every time. You have to declare them outside of the function and only reference them inside the code block