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POJavaScript function runs for 1 second then clears?
 

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  1. POJavaScript function runs for 1 second then clears?
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    <p>So I've written a web page with a few JavaScript functions.</p> <p>The page runs perfectly in Dreamweaver but when I tried it out in a browser (Google Chrome and Firefox) the JavaScript flashes for a split second then clears. I have no idea at all why this is. </p> <pre><code>&lt;body&gt; &lt;form name="myForm"&gt; &lt;ol&gt; &lt;li&gt; &lt;h1&gt; TILE CALCULATOR&lt;/h1&gt; &lt;/li&gt; &lt;li&gt; &lt;label for="wall height"&gt;Wall height (cm)&lt;/label&gt; &lt;input type="text" id="wall_height" /&gt; &lt;/li&gt; &lt;li&gt; &lt;label for="wall width"&gt;Wall Width (cm)&lt;/label&gt; &lt;input type="text" id="wall_width" /&gt; &lt;/li&gt; &lt;li&gt; &lt;label for="tile height"&gt;Tile Height (cm)&lt;/label&gt; &lt;input type="text" id="tile_height" /&gt; &lt;/li&gt; &lt;li&gt; &lt;label for="tile width"&gt;Tile Width (cm)&lt;/label&gt; &lt;input type="text" id="tile_width" /&gt; &lt;/li&gt; &lt;button onclick="javascript:validate();"&gt; Calculate &lt;/button&gt; &lt;/ol&gt; &lt;/form&gt; &lt;br /&gt; &lt;p id="result"&gt;&lt;/p&gt; &lt;br /&gt; &lt;canvas id="myCanvas"&gt; Your browser does not support this feature&lt;/canvas&gt; &lt;br /&gt; &lt;br /&gt; &lt;script language="javascript" type="text/javascript"&gt; //functoin to validate the inputs by the user //user can only enter a number and all fields must be filled function validate() { //first make sure canvas is clear clearCanvas() //take the inputs as variables var x = document.getElementById("tile_width").value; var y = document.getElementById("tile_height").value; var z = document.getElementById("wall_width").value; var i = document.getElementById("wall_height").value; //check if the user has entered nothing and alert if they have if (x==null || x=="" || y==null || y=="" || z==null || z=="" || i==null || i=="") { alert("All the fields have to be filled out!"); clearResult(); } // check if the user has entered invalid values, only numbers can be entered if (isNaN(x) == true || isNaN(y) == true || isNaN(z) == true || isNaN(i) == true) { alert("Dimensions can only be numbers!"); clearResult(); } //check for negatives if (x &lt;= 0 || y &lt;= 0 || z &lt;= 0 || i &lt;= 0) { alert("invalid dimension input, positive non-zero values only"); clearResult(); } //if valid calculate tiles and print else tileCalculator(); } function tileCalculator() { //take the input as variables var tileWidth = document.getElementById("tile_width").value; var tileHeight = document.getElementById("tile_height").value; var wallWidth = document.getElementById("wall_width").value; var wallHeight = document.getElementById("wall_height").value; //find the areas of the tile and the wall var tileArea = tileWidth * tileHeight; var wallArea = wallWidth * wallHeight; //divide these to find the number of tiles needed var noOfTiles = (wallArea/tileArea); //prints the result of noOfTiles document.getElementById("result").innerHTML=" The number of Tiles you will need are : " + noOfTiles; //scalled tiles to the canvas width of your choice var scalledWidth = 500; var ratioHW = wallHeight/wallWidth; var scalledHeight = ratioHW*scalledWidth; //scaled tile sizes //scale the tiles to correct pixels var scalledTileWidth = (tileWidth/wallWidth)*scalledWidth; var scalledTileHeight = (tileHeight/wallHeight)*300; //finds the number of tiles needs in a row var noWidth = wallWidth/tileWidth; //number of tiles in a column var noHeight = wallHeight/tileHeight; var canvas = document.getElementById("myCanvas"); canvas.style.width=scalledWidth + "px"; canvas.style.height=scalledHeight + "px"; printWall(0,0,noWidth,scalledTileWidth,(scalledTileHeight/2),noHeight); } //print a tile given the position and dimensions function printTile(x,y,tileWidth,tileHeight) { var c=document.getElementById("myCanvas"); var ctx=c.getContext("2d"); ctx.fillRect(x,y,tileWidth,tileHeight); } //prints one row of tiles given the starting position and number to be printed function printTileRow(x,y,numberOfTiles,tileWidth,tileHeight) { var start = 0; //loops upto number of tiles in a row while (start &lt; numberOfTiles) { //prints a tile each time printTile(x,y,tileWidth,tileHeight); //next brick position x = x + (tileWidth + 1); // add a space between tiles here. start++; } } //prints the wall function printWall(x,y,numberOfTiles,tileWidth,tileHeight,numberOfRows) { //holds whether last row was shifted var shiftCount = 0; //starting index var start = 0; //loop up adding a row until required number of rows while (start &lt; numberOfRows) { //prints half a tile at the start of each row printTile(0,y,(0.5 * tileWidth - 1),(tileHeight)); //prints the row printTileRow((x+shiftCount),y,numberOfTiles,tileWidth,tileHeight); //if shifted if (shiftCount &gt; 0) { //was shifted last row shiftCount = 0; } else { //was not shifted last row shiftCount = shiftCount + (0.5*tileWidth); } start++; //start next row y = y + (tileHeight + 1); } } //clears the canvus each time the button is pressed function clearCanvas() { //reset canvus to 300 by 300 and clear var canvas = document.getElementById("myCanvas"); var context = canvas.getContext('2d'); canvas.style.height="300px"; canvas.style.width="300px"; context.clearRect(0,0,300,300); } function clearResult() { document.getElementById("result").innerHTML=""; } &lt;/script&gt; &lt;/body&gt; </code></pre> <p>I would really appreciate it if someone could have a quick look for me! Thanks, </p>
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    1. COwhat is the planned behaviour of your javascript?
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    2. COit prints out a wall of tiles in a canvas and gives the result of the area. It prints the wall and gives the result in dreamweaver then stays there , in a browser its prints and gives the correct result but only flashes it on screen for a split second
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