Edit in JSFiddle

var canvas = document.createElement('canvas'),
    width = canvas.width = window.innerWidth, 
    height = canvas.height = window.innerHeight,
    halfWidth = width/2,
    halfHeight = height/2, 
    fov = 250;
     
var context = canvas.getContext('2d'); 
document.body.appendChild(canvas);

// set up an grid of 3D points that are laid 
// down horizontally on the floor

var pixels = []; 
for(var x = -250; x<250; x+=5) { 
    for(var z = -250; z<250; z+=5) { 
        var pixel = {x:x, y:40, z:z};
        pixels.push(pixel); 
    }
}

// call the render function 30 times a second
setInterval(render,1000/30); 


function render() { 

    // clear the canvas
    context.clearRect(0,0,width, height); 
    // and get the imagedata out of it
    var imagedata = context.getImageData(0, 0, canvas.width, canvas.height);
    
    // iterate through every point in the array
    var i=pixels.length; 
    while(i--){
        var pixel = pixels[i]; 
        
        // here's the 3D to 2D formula, first work out 
        // scale for that pixel's z position (distance from 
        // camera)
        var scale = fov/(fov+pixel.z); 
        // and multiply our 3D x and y to get our
        // 2D x and y. Add halfWidth and halfHeight
        // so that our 2D origin is in the middle of 
        // the screen.
        var x2d = (pixel.x * scale) + halfWidth; 
        var y2d = (pixel.y * scale) + halfHeight; 
        
        // and set that 2D pixel to be green
        setPixel(imagedata, x2d, y2d, 0, 255, 60); 
        
        // add 1 to the z position to bring it a little 
        // closer to the camera each frame
        pixel.z-=1;
        // if it's now too close to the camera, 
        // move it to the back
        if(pixel.z<-fov) pixel.z += (fov*2);
        
    }
    
    // and write all those pixel values into the canvas
    context.putImageData(imagedata,0,0); 
    
}

function setPixel(imagedata, x, y, r, g, b) {
    
    if((x<0) || (x>width) || (y<0) || (y>width)) return; 
    
    var i = ((y>>0) * imagedata.width + (x>>0)) * 4;

    imagedata.data[i] = r;
    imagedata.data[i+1] = g;
    imagedata.data[i+2] = b;
    imagedata.data[i+3] = 255;
}

body {
    background:black; 
    margin:0px; 
    overflow:hidden; 
}