Probs with: multi-line document.write ?

vmars316 · April 11, 2016

Hello & Thanks ,

I am trying to show a log from js to html page .

document.write(oneTraceLine + " <br>");}

But with the canvas element present , I don't seem to be able to do that .

The scaled down code exerpt below is an example of what I am trying to do ,

but actual js code is much much larger .

What can I do to get this puppy working ?

I am having trouble getting the <code> tags to work .

So , I'll try QUOTES next :

Hello & Thanks ,

I am trying to show a log from js to html page .

document.write(oneTraceLine + " <br>");}

But with the canvas element present , I don't seem to be able to do that .

The scaled down code exerpt below is an example of what I am trying to do ,

but actual js code is much much larger .

What can I do to get this puppy working ?

<!DOCTYPE html>
<html>
<head>

</head>
<body>
<img id="scream" src="http://www.w3schools.com/html/img_the_scream.jpg" alt="The Scream" width="220" height="277">
<p>Canvas:</p>
<canvas id="myCanvas" width="240" height="297" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.
</canvas>

<script type='text/javascript'>
window.onload = function() {
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var img = document.getElementById("scream");
alert("scream.width = " + scream.width + " , scream.height = " + scream.height +
"\n scream.src = " + scream.src );
ctx.drawImage(img, 10, 10);
traceIt();
}
function traceIt(){
var idTag = 0; var thisIdTag = 0; var cntFor = 9;
for(c=0; c<cntFor; c++) {
idTag += 1; thisIdTag += 2;
writeTraceLog('Here we go: idTag/thisIdTag \n' +
idTag+'/'+thisIdTag + ' ::' );
writeTraceLog('Here we go: idTag/thisIdTag \n' +
idTag+'/'+thisIdTag + ' ::' );
if(idTag == 8){
alert(' idTag/thisIdTag Should be: 8/16 \n' +
idTag+'/'+thisIdTag + ' ::');
}
}
}
//
function writeTraceLog(oneTraceLine){
document.open();
document.write(oneTraceLine + " <br>");}
document.open();
//

</script>

</body>
</html>

Edited April 11, 2016 by vmars316

Ingolme · April 11, 2016

You should not use document.write() because when called after the initial page load it will erase everything that is currently on the page before writing its output.

vmars316 · April 11, 2016

You should not use document.write() because when called after the initial page load it will erase everything that is currently on the page before writing its output.

Pls then , will you show me an example of what I should use ?

If I remove JUST the canvas element

and leave in the <p id="traceLog" > writeTraceLog <br></p>

it prints , but overlays itself .

Thanks

Edited April 11, 2016 by vmars316

Ingolme · April 11, 2016

The easiest alternative is innerHTML, but there are other methods using the DOM.

vmars316 · April 11, 2016

The easiest alternative is innerHTML, but there are other methods using the DOM.

Same deal , it overlays each line .

Ingolme · April 11, 2016

What does your code look like?

vmars316 · April 11, 2016

What does your code look like?

<!DOCTYPE html>

<html>

<head>

</head>

<body onload="startIt()">

<img id="scream" src="http://www.w3schools.com/tags/img_the_scream.jpg" alt="The Scream" width="220" height="277">

<p id="traceMsg"></p><p>Canvas:</p>

<canvas id="myCanvas" width="240" height="297" style="border:1px solid #d3d3d3;">

Your browser does not support the HTML5 canvas tag.

</canvas>

<script type='text/javascript'>

function startIt() {

var oneTraceLine ;

var canvas = document.getElementById("myCanvas");

var ctx = canvas.getContext("2d");

var img = document.getElementById("scream");

alert("scream.width = " + scream.width + " , scream.height = " + scream.height +

"\n scream.src = " + scream.src );

ctx.drawImage(img, 10, 10);

traceIt();

}

function traceIt(){

var idTag = 0; var thisIdTag = 0; var cntFor = 9;

for(c=0; c<cntFor; c++) {

idTag += 1; thisIdTag += 2;

writeTraceLog('Here we go: idTag/thisIdTag \n' +

idTag+'/'+thisIdTag + ' ::' );

writeTraceLog('Here we go: idTag/thisIdTag \n' +

idTag+'/'+thisIdTag + ' ::' );

if(idTag == 8){

continueOrCancel();

alert(' idTag/thisIdTag Should be: 8/16 \n' +

idTag+'/'+thisIdTag + ' ::');

}

}

}

//

function writeTraceLog(oneTraceLine){

document.getElementById("traceMsg").innerHTML = oneTraceLine;

}//

//

function continueOrCancel(){

var txt;

var r = confirm("Press OK to contimue... Else Press Cancel .");

if (r == true) {

txt = "You pressed OK!\n let's continue...";

} else

{

abortJS();

}

}

//

function abortJS(){

try {

adddlert("This is intentionally Bad Code , to FORCE ERROR !");

}

catch(err) {

document.getElementById("errMsg").innerHTML = err.message;

}

}

//

</script>

</body>

</html>

Edited April 11, 2016 by vmars316

justsomeguy · April 11, 2016

What do you mean it overlays, you see the text on top of some other element?

Ingolme · April 11, 2016

I don't see an element with id "traceMsg" in your code. That HTML element needs to exist on the page.

You also should use += if you don't want to overwrite previous messages.

document.getElementById("traceMsg").innerHTML += oneTraceLine

vmars316 · April 11, 2016

I don't see an element with id "traceMsg" in your code. That HTML element needs to exist on the page.

You also should use += if you don't want to overwrite previous messages.

document.getElementById("traceMsg").innerHTML += oneTraceLine

Ah Thanks !

The += in

document.getElementById("traceMsg").innerHTML += (oneTraceLine + "<br>");

is the piece I was missig .

The whole code now works great and looks like :

<!DOCTYPE html>

<html>

<head>

</head>

<body onload="startIt()">

<img id="scream" src="http://www.w3schools.com/tags/img_the_scream.jpg" alt="The Scream" width="220" height="277">

<p id="traceMsg"></p><p>Canvas:</p>

<canvas id="myCanvas" width="240" height="297" style="border:1px solid #d3d3d3;">

Your browser does not support the HTML5 canvas tag.

</canvas>

<script type='text/javascript'>

function startIt() {

var oneTraceLine ;

var canvas = document.getElementById("myCanvas");

var ctx = canvas.getContext("2d");

var img = document.getElementById("scream");

alert("scream.width = " + scream.width + " , scream.height = " + scream.height +

"\n scream.src = " + scream.src );

ctx.drawImage(img, 10, 10);

traceIt();

}

function traceIt(){

var idTag = 0; var thisIdTag = 0; var cntFor = 9;

for(c=0; c<cntFor; c++) {

idTag += 1; thisIdTag += 2;

writeTraceLog('Here we go: idTag/thisIdTag \n' +

idTag+'/'+thisIdTag + ' ::' );

writeTraceLog('Here we go: idTag/thisIdTag \n' +

idTag+'/'+thisIdTag + ' ::' );

if(idTag == 8){

continueOrCancel();

alert(' idTag/thisIdTag Should be: 8/16 \n' +

idTag+'/'+thisIdTag + ' ::');

}

}

}

//

function writeTraceLog(oneTraceLine){

document.getElementById("traceMsg").innerHTML += (oneTraceLine + "<br>");

}//

//

function continueOrCancel(){

var txt;

var r = confirm("Press OK to contimue... Else Press Cancel .");

if (r == true) {

txt = "You pressed OK!\n let's continue...";

} else

{

abortJS();

}

}

//

function abortJS(){

try {

adddlert("This is intentionally Bad Code , to FORCE ERROR !");

}

catch(err) {

document.getElementById("errMsg").innerHTML = err.message;

}

}

//

</script>

</body>

</html>

vmars316 · April 11, 2016

addendum:

BTW: The abort code above sometimes doesn't work ,

so I wrote new code here :

http://liesandcowpies.com/javascript/abortJS.html

I tried to Post it here , but couldn't get <code> or quote to work .

Edited April 12, 2016 by vmars316

Ingolme · April 12, 2016

What is "abort" supposed to do exactly?

thescientist · April 12, 2016

I tried to Post it here , but couldn't get <code> or quote to work .

The markup syntax is typically to surround it with brackets, eg [ code] code here [/ code] (spaces before code intentional). There is also a button for inserting it, the < > button.

vmars316 · April 12, 2016

thescientist ;

Hello & Thanks ,

Learning javascript from w3schools , I often the code there as a starting point .

But what happens when , I ask a question regarding code , I often paste that code into the question text .

But when I use the < code> or < quote> icons , often times it deletes part of the code .

For example , here is some code as regular text :

//

function writeTraceLog(oneTraceLine){

document.getElementById("traceMsg").innerHTML += ( "<br> " + oneTraceLine);

}

//

function continueOrCancel(){

var txt;

var r = confirm("Press OK to continue... Else... Press Cancel to Abort javascript .");

if (r == true) {

txt = "You pressed OK!\n let's continue...";

} else {

}

//

Here is the same code using < code> icon :

Well, well , it usually just deletes a few lines here and there . Today it deleted the whole code .

The problem is further troublesome , because it looks normal in the Edit and Preview window .

It isn't evident til I look at what actually gets posted .

Here is the same code as < quote> :

//

function writeTraceLog(oneTraceLine){

document.getElementById("traceMsg").innerHTML += ( "<br> " + oneTraceLine);

}

//

function continueOrCancel(){

var txt;

var r = confirm("Press OK to continue... Else... Press Cancel to Abort javascript .");

if (r == true) {

txt = "You pressed OK!\n let's continue...";

} else {

}

}

//

Hmm , its working today .

Here is the same code plugging in the < code> manually :

< code>

//

function writeTraceLog(oneTraceLine){

document.getElementById("traceMsg").innerHTML += ( "<br> " + oneTraceLine);

}

//

function continueOrCancel(){

var txt;

var r = confirm("Press OK to continue... Else... Press Cancel to Abort javascript .");

if (r == true) {

txt = "You pressed OK!\n let's continue...";

} else {

}

//

</ code>

Hmm... The code is there , but no colored background .

Anyways , just thought I would mention it .

Edited April 12, 2016 by vmars316

justsomeguy · April 12, 2016

All bbcode tags use square brackets, not angle brackets.

vmars316 · April 12, 2016

What is "abort" supposed to do exactly?

It is supposed to Exit the script . which it does , always , all browsers .

Ingolme · April 12, 2016

Forcing an error is not a really good way to program. You could wrap the whole thing in a function and call return instead. It's more efficient and won't interfere with other unrelated scripts that may be running.

function myProgram() {
  // All code in here
  if(wantToLeave) {
    return;
  }
}

thescientist · April 12, 2016

I usually don't even bother with the button. It's just easier to set the bbcode tags myself, eg.

[ code]

function showCodeSnippet() {

//my code will go here

}

[/ code]

(again don't include the space before code)

vmars316 · April 13, 2016

I usually don't even bother with the button. It's just easier to set the bbcode tags myself, eg.

[ code]

function showCodeSnippet() {

//my code will go here

}

[/ code]

(again don't include the space before code)

Oh , I interpreted "(spaces before code intentional)." to mean this is how to do it . Thanks

vmars316 · April 13, 2016

Forcing an error is not a really good way to program. You could wrap the whole thing in a function and call return instead. It's more efficient and won't interfere with other unrelated scripts that may be running.
function myProgram() {
  // All code in here
  if(wantToLeave) {
    return;
  }
}

Hey , that's much better . Thanks

vmars316 · April 13, 2016

Forcing an error is not a really good way to program. You could wrap the whole thing in a function and call return instead. It's more efficient and won't interfere with other unrelated scripts that may be running.
function myProgram() {
  // All code in here
  if(wantToLeave) {
    return;
  }
}

Oops , its not working for me .

Pls , what am I doing wrong ?

<code>

function continueOrCancel(){

var x;

var r = confirm(" function continueOrCancel() \nPress OK to continue...\nElse\nPress Cancel to Abort javascript .");

if (r == true) {

alert("You pressed OK! Let's Continue...");

} else {

if(true){alert(" function continueOrCancel()\nInside ELSE , r= " + r);

return;

}

<code>

Thanks

Ingolme · April 13, 2016

You have to call return in the function that you want to end, not in a sub function.

This should work:

function continueOrCancel(){
  return confirm("Press OK to contimue... Else Press Cancel .");
}

In the original function:

    if(idTag == 8){
      if(continueOrCancel()) {
        // Continue
        alert(' idTag/thisIdTag Should be: 8/16  \n' + idTag+'/'+thisIdTag + ' ::');
      } else {
        // Cancel
        return;
      }
    }

dsonesuk · April 13, 2016

'[' and ']' NOT '<' and '>', HOW MANY MORE TIMES! We have to explain for placement of code in post.

vmars316 · April 14, 2016

'[' and ']' NOT '<' and '>', HOW MANY MORE TIMES! We have to explain for placement of code in post.

Ouch . Sorry , my dyslexia gets the best of me sometimes .

I've seen the term 'bbcode' .

Until , you used the term 'bbcode' in this context , I didn't realize that this markup is called 'bbcode' .

Also , it would be more clear (to me) if the icons used above were '

' and '

' .
Anyways , I've got it now .

Thanks

Edited April 14, 2016 by vmars316

Probs with: multi-line document.write ?

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