CODEWITHSUNDEEP
javascriptundefined
Bojana Cubranovic
Bojana Cubranovic

Reputation: 39

undefined value javascript

I'm trying to run a javascript function with values ​​but gets the answer val is undefined.

I want to append this value

Function run

myufunc("test msg");

code

function myufunc(val){
    var script   = document.createElement("script");
    script.type  = "text/javascript";
    script.text  = 'alert(val);';
    document.body.appendChild(script);
}

Upvotes: 2

Views: 87

Answers (4)

MrCode
MrCode

Reputation: 64526

The issue is val is only available in the myufunc scope, and when your script is appended, it is executed in the global scope, not your function scope. Thus, val is not defined in the global scope.

A solution is to create a global variable and set its value to val, then use the global in the alert. Using this way, there is no need to concatenate the variable into the string, and so you don't have the problem of the variable containing quotes and breaking the string.

Fiddle

function myufunc(val){
    myValue = val; // create global

    var script   = document.createElement("script");
    script.type  = "text/javascript";
    script.text  = 'alert(myValue);'; // use the global
    document.body.appendChild(script);
}

The following will all work:

myufunc('test');
myufunc('tes"t');
myufunc("tes't");

Upvotes: 0

Chris Fremgen
Chris Fremgen

Reputation: 5358

First, "int" is a reserved word in Javascript-

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Reserved_Words

Second, you are using "val" as if it were a string, not a variable.

init("test msg");

function init(val){

var script   = document.createElement("script");
script.type  = "text/javascript";
script.text  = 'alert('+val+');';
document.body.appendChild(script);

}

Upvotes: 1

Filip Roséen
Filip Roséen

Reputation: 63797

The problem

The problem is that your created script-tag will contain alert(val), but val hasn't been initialized; it does exists inside your function - but the newly created script-element have no idea what val you are referring to.

You probably want the element to end up containing alert("test msg");:

function f(val){
  var script   = document.createElement("script");
  script.type  = "text/javascript";
  script.text  = 'alert("' + val + '");';
  document.body.appendChild(script);
}

f ("test msg"); // will create a <script> containing `alert("test msg");`

Note: since we are manually wrapping the contents of val with double-quotes, be careful so that the passed in value itself doesn't contain a double-quote "; this will break the "generated" code.

Upvotes: 7

Tyler McGinnis
Tyler McGinnis

Reputation: 35276

int is a reserved word in JavaScript, so definitely don't use it. That's most likely the reason your code isn't working properly.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Reserved_Words

Upvotes: 1

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