警报中的算术方程式?

时间:2015-06-02 23:41:50

标签: javascript math alert dialog

您好我正在发出警报,显示在警告框中添加了Number(num1)+ Number(num2)它提供了用户输入和结果,但我想知道如何编写它以显示整个等式,例如," 2 + 2 = 4"如果用户输入2和2。

我知道如何让它显示结果,但是如何让它显示用户输入的数字以获得结果?

1 个答案:

答案 0 :(得分:0)

假设我明白你想做什么:

( function( $ ) {

$( function() {



    $(document).ready(function () {

        $(".StartButton").click(function () {
            $(".SplashScreen").hide();
            $(".FinishScreen").hide();
            $("#canvasArea").show();
            init();
        });

        //Canvas stuff
        var canvas = $("#canvasArea")[0];
        var ctx = canvas.getContext("2d");
        var w = $("#canvasArea").width();
        var h = $("#canvasArea").height();

        //Lets save the cell width in a variable for easy control
        var sw = 10;
        var direction;
        var nd;
        var food;
        var score;

        //Lets create the snake now
        var snake_array; //an array of cells to make up the snake

        function endGame() {
            $("#canvasArea").hide();
            $("#score").text(score);
            $(".FinishScreen").show();
        }

        function init() {
            direction = "right"; //default direction
            nd = [];
            create_snake();
            create_food(); //Now we can see the food particle
            //finally lets display the score
            score = 0;

            //Lets move the snake now using a timer which will trigger the paint function
            //every 60ms
            if (typeof game_loop != "undefined") clearInterval(game_loop);
            game_loop = setInterval(paint, 60);
        }

        function create_snake() {
            var length = 5; //Length of the snake
            snake_array = []; //Empty array to start with
            for (var i = length - 1; i >= 0; i--) {
                //This will create a horizontal snake starting from the top left
                snake_array.push({
                    x: i,
                    y: 0
                });
            }
        }

        //Lets create the food now
        function create_food() {
            food = {
                x: Math.round(Math.random() * (w - sw) / sw),
                y: Math.round(Math.random() * (h - sw) / sw),


            };
            //This will create a cell with x/y between 0-44
            //Because there are 45(450/10) positions accross the rows and columns

        }

        //Lets paint the snake now
        function paint() {
            if (nd.length) {
                direction = nd.shift();
            }

            //To avoid the snake trail we need to paint the BG on every frame
            //Lets paint the canvas now
            ctx.fillStyle = "#0056a0";
            ctx.fillRect(0, 0, w, h);
            ctx.strokeStyle = "#ffffff";
            ctx.strokeRect(0, 0, w, h);

            //The movement code for the snake to come here.
            //The logic is simple
            //Pop out the tail cell and place it infront of the head cell
            var nx = snake_array[0].x;
            var ny = snake_array[0].y;

            //These were the position of the head cell.
            //We will increment it to get the new head position
            //Lets add proper direction based movement now
            if (direction == "right") nx++;
            else if (direction == "left") nx--;
            else if (direction == "up") ny--;
            else if (direction == "down") ny++;

            //Lets add the game over clauses now
            //This will restart the game if the snake hits the wall
            //Lets add the code for body collision
            //Now if the head of the snake bumps into its body, the game will restart
            if (nx == -1 || nx == w / sw || ny == -1 || ny == h / sw || check_collision(nx, ny, snake_array)) {
                //end game
                return endGame();
            }

            //Lets write the code to make the snake eat the food
            //The logic is simple
            //If the new head position matches with that of the food,
            //Create a new head instead of moving the tail
            if (nx == food.x && ny == food.y) {
                var tail = {
                    x: nx,
                    y: ny
                };
                score++;

                //Create new food
                create_food();
            } else

            {
                var tail = snake_array.pop(); //pops out the last cell
                tail.x = nx;
                tail.y = ny;
            }

            //The snake can now eat the food.
            snake_array.unshift(tail); //puts back the tail as the first cell

            for (var i = 0; i < snake_array.length; i++) {
                var c = snake_array[i];

                //Lets paint 10px wide cells
                paint_cell(c.x, c.y);
            }

            //Lets paint the food
            paint_cell(food.x, food.y);

            //Lets paint the score
            var score_text = "Score: " + score;
            ctx.fillStyle = "#ffffff";
            ctx.fillText(score_text, 5, h - 5);

            //Set the font and font size
            ctx.font = '12px Arial';

            //position of the fill text counter
            ctx.fillText(itemCounter, 10, 10);

        }

        //Lets first create a generic function to paint cells
        function paint_cell(x, y) {
            ctx.fillStyle = "#d8d8d8";
            ctx.fillRect(x * sw, y * sw, sw, sw);
        }

        function check_collision(x, y, array) {
            //This function will check if the provided x/y coordinates exist
            //in an array of cells or not
            for (var i = 0; i < array.length; i++) {
                if (array[i].x == x && array[i].y == y) return true;
            }

            return false;
        }

        // Lets prevent the default browser action with arrow key usage
        var keys = {};
        window.addEventListener("keydown",
            function(e){
                keys[e.keyCode] = true;
                switch(e.keyCode){
                    case 37: case 39: case 38:  case 40: // Arrow keys
                    case 32: e.preventDefault(); break; // Space
                    default: break; // do not block other keys
                }
            },
        false);
        window.addEventListener('keyup',
            function(e){
                keys[e.keyCode] = false;
            },
        false);


        //Lets add the keyboard controls now
        $(document).keydown(function (e) {
            var key = e.which;
            var td;
            if (nd.length) {
                var td = nd[nd.length - 1];

            } else {
                td = direction;
            }

            //We will add another clause to prevent reverse gear
            if (key == "37" && td != "right") nd.push("left");
            else if (key == "38" && td != "down") nd.push("up");
            else if (key == "39" && td != "left") nd.push("right");
            else if (key == "40" && td != "up") nd.push("down");

            //The snake is now keyboard controllable

        });

    });


    $(document).on('click', '.button-pad > button', function(e) {
        if ($(this).hasClass('left-btn')) {
            e = 37;
        }
        else if ($(this).hasClass('up-btn')) {
            e = 38;
        }
        else if ($(this).hasClass('right-btn')) {
            e = 39;
        }
        else if ($(this).hasClass('down-btn')) {
            e = 40;
        }
        $.Event("keydown", {keyCode: e});
    }); 

});

})( jQuery );