如何在更新的php响应中更改js变量

Question

如何在返回特定php会话变量响应时运行的js脚本中更改已定义的变量？

如果设置了特定的php会话变量，我将如何更改此canvas js数组中的颜色。我现在使用的方法导致了一个问题，即增加动画的速度，尽管颜色确实发生了变化。

   <div id="isohold">  
<canvas id="iso"></canvas>
<div id="loghold">Login</div>
</div>   

  <?php
    session_start();                
    //3.1.4 if the user is logged in Greets the user with message
    if (isset($_SESSION['userid'])){
    $userid = $_SESSION['userid'];


    echo " <script>

'use strict';


var rn = function rn(min, max) {
    return Math.random() * (max - min) + min;
};
var ctx = iso.getContext('2d');

var _window = window;
var w = _window.innerWidth;
var h = _window.innerHeight;

var t = 10;
var arr = [];
var cn = 200;
var rad = 300;
var sp = rn(1, 5) / 10000;
iso.width = w;
iso.height = h;

while (~ ~ cn--) {
    var angle = rn(110, 359);

    arr = [].concat(arr, [{
        color: 'rgba(81, 180, 200, 0.5)',
        distortion: rn(15, 75),
        tmod: rn(5, 10),
        size: rn(15, 20),
        speed: 0.0005,
        angle: angle,
        lastPos: {
            x: w / 2,
            y: h / 2
        }
    }]);
}

var draw = function draw() {
    request = requestAnimationFrame(function () {
        return draw();
    });
    t++;

    ctx.globalCompositeOperation = 'source-over';
    ctx.fillStyle = 'rgba(0, 0, 0,.1)';
    ctx.fillRect(0, 0, w, h);

    var crad = rad * Math.sin(300);

    ctx.globalCompositeOperation = 'lighter';
    arr.forEach(function (el) {
        ctx.strokeStyle = el.color;
        ctx.lineWidth = el.size;
        ctx.beginPath();

        var lastPos = el.angle - 0.0005;
        var x = w / 2 + (crad + el.distortion * Math.sin(t / el.tmod)) * Math.cos(el.angle * 180 / Math.PI);
        var y = h / 2 + (crad + el.distortion * Math.sin(t / el.tmod)) * Math.sin(el.angle * 180 / Math.PI);

        ctx.moveTo(el.lastPos.x, el.lastPos.y);
        ctx.lineTo(x, y);

        el.lastPos = { x: x, y: y };
        el.angle = (el.angle + 0.0005) % 359;
        ctx.stroke();
    });
};

var resize = function resize() {
    iso.width = w = window.innerWidth;
    iso.height = h = window.innerHeight;
};

var request = requestAnimationFrame(function () {
    return draw();
});
window.addEventListener('resize', function () {
    return resize();
});

</script>    
<script>
                 $(\"#loghold\").hide();   
</script>       
            ";
    }else{
    echo "<script>

'use strict';

var rn = function rn(min, max) {
    return Math.random() * (max - min) + min;
};
var ctx = iso.getContext('2d');

var _window = window;
var w = _window.innerWidth;
var h = _window.innerHeight;

var t = 10;
var arr = [];
var cn = 200;
var rad = 300;

iso.width = w;
iso.height = h;

while (~ ~ cn--) {
    var angle = rn(110, 359);

    arr = [].concat(arr, [{
        color: 'rgba(255, 255, 255, 0.5)',
        distortion: rn(15, 75),
        tmod: rn(5, 10),
        size: rn(15, 20),
        speed: rn(1, 5) / 5000,
        angle: angle,
        lastPos: {
            x: w / 2,
            y: h / 2
        }
    }]);
}

var draw = function draw() {
    request = requestAnimationFrame(function () {
        return draw();
    });
    t++;

    ctx.globalCompositeOperation = 'source-over';
    ctx.fillStyle = 'rgba(0, 0, 0,.1)';
    ctx.fillRect(0, 0, w, h);

    var crad = rad * Math.sin(300);

    ctx.globalCompositeOperation = 'lighter';
    arr.forEach(function (el) {
        ctx.strokeStyle = el.color;
        ctx.lineWidth = el.size;
        ctx.beginPath();

        var lastPos = el.angle - el.speed;
        var x = w / 2 + (crad + el.distortion * Math.sin(t / el.tmod)) * Math.cos(el.angle * 180 / Math.PI);
        var y = h / 2 + (crad + el.distortion * Math.sin(t / el.tmod)) * Math.sin(el.angle * 180 / Math.PI);

        ctx.moveTo(el.lastPos.x, el.lastPos.y);
        ctx.lineTo(x, y);

        el.lastPos = { x: x, y: y };
        el.angle = (el.angle + el.speed) % 359;
        ctx.stroke();
    });
};

var resize = function resize() {
    iso.width = w = window.innerWidth;
    iso.height = h = window.innerHeight;
};

var request = requestAnimationFrame(function () {
    return draw();
});
window.addEventListener('resize', function () {
    return resize();
});

</script>          
            ";           


  };

 ?>

Answer 1

    <?php $color="yellow"; ?>     <!--define it in php-->

    <div id="color" data-color= <?php echo $color; ?> ></div>    <!--insert it in html-->

    <script>
    var color="";    //declare your variable in JS
    window.onload = function(e) {
    color=document.getElementById("color").dataset.color;     //redefine the variable's value from the html defined by the php
    };
    </script>