Use split()
function in javascript and java
eg:
In javascript
var metadata = "form=string=a||list=string=a|b|c||isTrue=boolean=true";
var meta = metadata.split("||");
console.log(meta[0]);
In java
String metadata = "form=string=a||list=string=a|b|c||isTrue=boolean=true";
String[] meta = metadata.split("\\|\\|");
System.out.println( meta[0] );