Question

My string is something like

var query = "@id >= 4 OR @id2 < 6 AND @id3 >= 5 AND @name = foo "

Now what I would like to do with this string is to reverse every “equality” test.
Replacing ‘ >=’ by ‘ <‘ , ‘ <‘ by ‘ >=’ and ‘ =’ by ‘ !=’ .

The result I want :

var reverseQuery = "@id < 4 OR @id2 >= 6 AND @id3 < 5 AND @name != foo "

We can’t use :

reverseQuery = query.replace(/>=/g, "<").replace(/</g, ">=").etc

Because the result of this would be

@id >= 4 OR @id2 >= 6 AND @id3 >= 5 AND @name != foo 

Right ? So how to do this nicely ?

Thanks,

Answer 1

Use a single replace with a callback function that determines the replacement.

query = query.replace(/(<=?|>=?|=|<>|!=)/g, function(m){
  switch(m) {
    case '<': return '>=';
    case '>': return '<=';
    case '<=': return '>';
    case '>=':return '<';
    case '=': return '!=';
    case '<>': return '=';
    case '!=': return '=';
  }
});

Demo: http://jsfiddle.net/Guffa/s2xj5/