javascript regex pattern for _water_glass

Question

I need a javascript regex pattern to test a schema variable, so that it should have either of the following.

1. It can start with any character followed by "_water_glass" and must not be anything after water_glass like "xxxx_water_glass"

or

2. It can be just "water_glass" not necessary to have character before water_glass and must not be anything after water_glass.

Could anyone help on this please to get the regex pattern.

Answer 1

Try this simply /^.*_?\_water_glass/

    var re = /^.*_?_water_glass/mg; 
var str = 'horse.mp3_country_code\n4343434_country_code\n_country_code';
var m;

while ((m = re.exec(str)) != null) {
    if (m.index === re.lastIndex) {
        re.lastIndex++;
    }
    // View your result using the m-variable.
    // eg m[0] etc.
}

DEMO https://regex101.com/r/gB9zL7/2

Answer 2

Here you are:

^(?:.+_|)water_glass$

Details:

• ^- start of string
• (?:.+_|) - an optional 1+ chars other than line break chars, as many as possible, up to the last _ including it
• water_glass - a water_glass substring
• $ - end of string.

See this regex demo and a demo code below:

var re = /^(?:.+_|)water_glass$/gm; 
var str = 'xxxx_water_glass\nwater_glass';
var m;

while ((m = re.exec(str)) != null) {
    if (m.index === re.lastIndex) {
        re.lastIndex++;
    }
    // View your result using the m-variable.
    // eg m[0] etc.
}