You can use a matching regex solution:

text.match(/(?:L\+R|[^+])+/g)

See the regex demo. Details:

• (?: - start of a non-capturing group:
  • L\+R - L+R string
  • | - or
  • [^+] - any char other than +
• )+ - end of the group, one or more occurrences.

See the JavaScript demo:

var text = '23DGERA@SPK_20W L+R FA-2@1+342HSHC@CPU_8PIN INTEL_TEST!@1+2356GHMX@SSD_256G MICRON_CONTENT@2';
console.log(text.match(/(?:L\+R|[^+])+/g));

ECMAScript 2018+ compliant solution

In case you want to migrate to a more modern ECMAScript flavor, you can use

text.split(/\+(?<!L\+(?=R))/)

This will match a + that is not part of an L+R string.

const text = '23DGERA@SPK_20W L+R FA-2@1+342HSHC@CPU_8PIN INTEL_TEST!@1+2356GHMX@SSD_256G MICRON_CONTENT@2';
console.log(text.split(/\+(?<!L\+(?=R))/));

See the regex demo.

Instead of splitting on a + you could match the format in the example data.

First match a part containing a single @, and then match till the first occurrence of @ followed by a digit.

Note that the second match will be 342HSHC@CPU_8PIN INTEL_TEST!@1 instead of 342HSHC@CPU_8PIN INTEL_TEST!@2

\w+@\w+ [^@]*@\d\b

The pattern matches:

• \w+@\w+ Match 1+ word characters, @ and at 1+ word characters
• [^@]*@ Match a space, optional chars other than @, then match @
• \d\b Match a digit and a word boundary to prevent a partial match

Regex demo

const s = "23DGERA@SPK_20W L+R FA-2@1+342HSHC@CPU_8PIN INTEL_TEST!@1+2356GHMX@SSD_256G MICRON_CONTENT@2 + blablabla";
const regex = /\w+@\w+ [^@]*@\d\b/g;
console.log(s.match(regex));

The string looks like a list of parts each with a quantity e.g. @1. You can use that to identify the correct + characters to split on.

Using a look-behind containing @\d+ -> (?<=@\d+) followed by the character you want to match (escaped because + has a special meaning) gives:

(?<=@\d+)\+

Using this in code we also need specify the g modifier to match all instances instead of just the first one.

const str =  '23DGERA@SPK_20W L+R FA-2@1+342HSHC@CPU_8PIN INTEL_TEST!@1+2356GHMX@SSD_256G MICRON_CONTENT@2'
const items = str.split(/(?<=@\d+)\+/g);

console.log(items);