To create a link "Back" that allow come back to previous page before current, I use a variable called $_SERVER['HTTP_REFERER']. Hereafter, you will see a example:
... <body> ... <a href="<?php echo $_SERVER['HTTP_REFERER']?>">Back</a> ... </body> ...
Be careful when you refresh the page!
I was programming a Web app and I noticed that always insert address of Web app, I had to type "www.mywebapp.com/index.php" to show up a web page. If I just type the next address "www.mywebapp.com", the Web server (Apache) list the directories and some files.
I would rather type "www.mywebapp.com" and same time the Web server show up the index.php. But how can I do that? Just follow the next steps:
| <script type="text/javascript"> function drawLine(context,startX,startY,endX,endY,color){ context.beginPath(); context.moveTo(startX,startY); context.lineTo(endX,endY); context.closePath(); context.strokeStyle=color; context.stroke(); } function drawRectangle(context,startX,startY,width,height,fill){ context.beginPath(); context.rect(startX,startY,width,height); context.closePath(); context.stroke(); if(fill) context.fill(); } function clearCanvas(context){ // Store the current transformation matrix context.save(); // Use the identity matrix while clearing the canvas context.setTransform(1, 0, 0, 1, 0, 0); context.clearRect(0, 0, myCanvas.width, myCanvas.height); // Restore the transform context.restore(); } function drawBarChart(context,data,startX,startY,endX, endY,chartHeight,barWidth,markDataIncrementsIn,scale){ //draw x-axis drawLine(context,startX,startY,endX,startY,"#000"); //draw y-axis drawLine(context,startX,startY,startX,endY,"#000"); var maxValue=0; for(var i=0;i<data.length;i++){ //extract data var values = data[i].split(","); //column name var name=values[0]; //column value var height=parseFloat(values[1])*scale; //find maximum value if(parseInt(height)>parseInt(maxValue)) maxValue=height; //write data to chart //fill rectangle with yellow color context.fillStyle="#ff0"; drawRectangle(context,startX+(i*barWidth*2),(startY-height),barWidth,height,true); //add column title to x-axis context.textAlign="left"; //text color is black context.fillStyle="#000"; context.fillText(name,startX+(i*barWidth*2),(chartHeight-25),barWidth*2); } //add some data markers to y-axis var numMarkers = Math.ceil(maxValue/parseInt(markDataIncrementsIn)); context.textAlign="right"; context.fillStyle="#000"; var markerValue=0; for(var i=0;i<=numMarkers;i++){ context.fillText((markerValue/parseInt(scale)),(startX-5),(startY-markerValue),50); if(i==0){ drawLine(context,startX,(startY-markerValue),endX,(startY-markerValue),"#000"); }else{ drawLine(context,startX,(startY-markerValue),endX,(startY-markerValue),"#00f"); } markerValue+=parseInt(markDataIncrementsIn); } } function graph(scale){ var s=0; var changed=false; document.getElementById("range").innerHTML=scale; if(scale==undefined){ s=1; changed=false; }else{ s=scale; changed=true; } var graphCanvas = document.getElementById("myCanvas"); //ensure that element is available within DOM if(graphCanvas && graphCanvas.getContext){ //open a 2d context within canvas var context = graphCanvas.getContext("2d"); //bar chart data var data = new Array(5); data[0]="Bad,2"; data[1]="Mediocre,0.45"; data[2]="Sufficient,5.5"; data[3]="Good,7.2"; data[4]="Excelent,3.9"; //draw bar chart if(!changed){ drawBarChart(context,data,35,560,750,50,myCanvas.height,30,s,s); }else{ //clear canvas to redrawing clearCanvas(context); //draw bar chart drawBarChart(context,data,35,560,750,50,myCanvas.height,30,s,s); } } return true; } </script> |
| <body onload="graph(1);"> <div id="title">Grades</div> <table> <tr> <td><canvas id="myCanvas" width="800" height="600"></canvas><td> <td> <table> <tr> <td>Scale : <span id="range">1</span></td> </tr> <tr> <td><input type="range" min="1" max="501" value="1" onchange="return graph(this.value)"/></td> </tr> </table> </td> </tr> </table> </body> |
| <style type="text/css"> #title{ text-align: center; } </style> |
| <head> <link rel="stylesheet" type="text/css" href="style.css" /> <script type="text/javascript" src="functions.js"></script> </head> |
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Note: I made a mistake to input "192.168.1.199" instead a right IP address which is localhost or 127.0.0.1.
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