Regular Expression to get a number between two strings in Javascript

Question

Here are samples:

• example 1: string1<span id="header">5655811</span>string2
• example 2: string3<span id="header">51481</span>string4
• example 3: string5<span id="header">854211</span>string6

How can I get the number between <span id="header"> and </span> with JavaScript regex?

Answer 1

It depends on how safe you want to be. If you're sure that all of your input looks exactly like you have in your message, you can use:

var n = Number( input.match( /<span id="header">(\d+)<\/span>/ )[1] );

A slightly safer version would be:

var n;
var match = input.match( /<span id="header">\s*(\d+)\s*<\/span>/ );
if( match ) {
    n = Number( match[1] );
} else {
    // do error handling here
}