Javascript String Length
Advanced scripters will often need to know how long a Javascript string is. For
example, if a webdeveloper was creating a submission form that required the username
to be no longer than 20 characters, then she would need to check the length of the string
before allowing the user to submit data.
String Length Property
The length property returns the number of characters that are in a string, using
an integer. Below is the basic code for accessing this property.
Javscript Code:
<script type="text/javascript">
var myString = "123456";
var length = myString.length;
document.write("The string is this long: " + length);
// Same thing, but using the property inside the write function
document.write("<br />The string is this long: " + myString.length);
</script>
Display:
Change the String? Length Might Change
If you were to reference the length property after concatenating (adding) some characters to the string, then
the property will reflect these changes. Think of this as a reminder to only check the length of the string after you are sure
it isn't going to be changed.
Javscript Code:
<script type="text/javascript">
var myString = "123456";
document.write("The string is this long: " + myString.length);
myString = myString + "7890";
document.write("<br />The string is now this long: " + myString.length);
</script>
Display:
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