"Fit All in Window" command in Illustrator

fitAll.jsx

function calcRect(rectArray) {
    var rect = {
        rect  : rectArray.join(", "),
        topLeft : {
            x : rectArray[0],
            y : rectArray[1],
        },
        bottomRight : {
            x : rectArray[2],
            y : rectArray[3],
        },
    };
    rect.width  = Math.abs(rect.bottomRight.x - rect.topLeft.x);
    rect.height = Math.abs(rect.bottomRight.y - rect.topLeft.y);
    rect.center = [
        rect.topLeft.x + (rect.width / 2),
        rect.topLeft.y - (rect.height / 2)
    ];
    rect.aspectRatio = rect.width / rect.height;
    return rect;
}

function calcViewRect(rectArray, zoom) {
    var rect = {
        rect  : rectArray.join(", "),
        topLeft : {
            x : rectArray[0],
            y : rectArray[1],
        },
        bottomRight : {
            x : rectArray[2],
            y : rectArray[3],
        },
    };
    rect.width        = Math.abs(rect.bottomRight.x - rect.topLeft.x);
    rect.height       = Math.abs(rect.bottomRight.y - rect.topLeft.y);
    rect.zoom         = zoom || 1;
    rect.actualWidth  = rect.width * zoom;
    rect.actualHeight = rect.height * zoom;
    rect.aspectRatio  = rect.width / rect.height;
    return rect;
}

function getDocumentBounds(artboards) {
    var rect = {
        topLeft : {
            x : null,
            y : null,
        },
        bottomRight : {
            x : null,
            y : null,
        },
    };
    
    for (var i = 0; i < artboards.length; i++) {
        var artboardRect = calcRect(artboards[i].artboardRect);
        
        if (rect.topLeft.x == null) {
            rect.topLeft.x = artboardRect.topLeft.x;
        } else {
            if (artboardRect.topLeft.x < rect.topLeft.x) {
                rect.topLeft.x = artboardRect.topLeft.x;
            }
        }
        
        if (rect.topLeft.y == null) {
            rect.topLeft.y = artboardRect.topLeft.y;
        } else {
            if (artboardRect.topLeft.y > rect.topLeft.y) {
                rect.topLeft.y = artboardRect.topLeft.y;
            }
        }
                
        if (rect.bottomRight.x == null) {
            rect.bottomRight.x = artboardRect.bottomRight.x;
        } else {
            if (artboardRect.bottomRight.x > rect.bottomRight.x) {
                rect.bottomRight.x = artboardRect.bottomRight.x;
            }
        }
        
        if (rect.bottomRight.y == null) {
            rect.bottomRight.y = artboardRect.bottomRight.y;
        } else {
            if (artboardRect.bottomRight.y < rect.bottomRight.y) {
                rect.bottomRight.y = artboardRect.bottomRight.y;
            }
        }
    }
    rect.rect = [rect.topLeft.x, rect.topLeft.y, rect.bottomRight.x, rect.bottomRight.y];
    return rect;
}

function calcZoom(viewRect, documentRect, margin) {
    if (documentRect.aspectRatio > viewRect.aspectRatio) {
        return parseFloat(((viewRect.actualWidth - (2 * margin)) / documentRect.width).toFixed(2));
    } else {
        return parseFloat(((viewRect.actualHeight - (2 * margin)) / documentRect.height).toFixed(2));
    }
}

function fitAll(document) {
    var view         = document.views[0];
    
    var viewRect     = calcViewRect(view.bounds, view.zoom);
    var documentRect = calcRect(getDocumentBounds(document.artboards).rect);

    view.centerPoint = documentRect.center;
    view.zoom        = calcZoom(viewRect, documentRect, 20);
}

// fitAll(app.activeDocument);