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certain character, plus amount of characters required

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Aug 06.2008

I am very new to JavaScript.

I have a form which asks this question:

“Enter your student ID #: ” <input type=”text”….etc

I need a function which requires a total of 9 characters, and it must begin with the letter ‘L’. There should simply be an alert message which states the correct format if the user does not enter it correctly.

Can anyone help me out?

I can read and understand a lot of JavaScript, but am not proficient in it at all.

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JavaScript

3 Comments(s) ↴

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@Declan1991Aug 06.2008 — You can use a regexp. You should check on the server too though.

/^L.{8}$/

Something like<i>
</i>&lt;input type="text" onblur="if (!/^L.{8}$/.test(this.value)) alert('YOUR MESSAGE HERE');"&gt;
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@Marshmellow_ManauthorAug 06.2008 — That was a great suggestion and it works.

Could you tell me a way to do something similar. A number is required for another field, and it must be less than 30.

Dan
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@Declan1991Aug 06.2008 — if (isNaN(this.value) || Number(this.value) < 0 || Number(this.value > 30))
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