JavaScript Regex match only if character occurs only ones followed by alphanumeric character

Question

I want a JavaScript Regex which matches the character & only if it occurs exactly one time followed by a alphanumeric character.

Examples:

• &De&&let&&&e A&ll → Should only match &D and &l
• Hum&&an&s → should only match &s

This is what I have come up with but it is not quite right:

(?:[^\&]|^)\&([a-zA-Z0-9])

 var strings = `&De&&let&&&e A&ll Hum&&an&s` console.log( strings.match(/(?:[^\\&]|^)\\&([a-zA-Z0-9])/g) ) 

Answer 1

You can turn the first group into a capturing group so that you could restore the value inside the replaced string with a $1 placeholder (also called replacement backreference ). In the similar way, you may restore the alphanumeric char captured into another group.

Here is an example of replacing & with # in the contexts you defined:

 var strs = ['&De&&let&&&e A&ll', 'Hum&&an&s']; var rx = /(^|[^&])&([A-Z0-9])/gi; for (var s of strs) { console.log(s.replace(rx, "$1#$2")); }