Else Works Everytime, While If I Remove Else Block, Everything Works Perfect [closed]

So this is my code

stem = "/*smth*/"
for (var i = stem.length - 1; i >= 0; i--) {
    if (stem[i] == 'ա' && stem[i-1] == 'ե' && stem[i+1] != undefined) {
        var alternated = stem.slice(0, i) + stem.slice(i+1)
    } else if (stem[i] == 'ե' && stem[i+1] == 'ւ' && stem[i+2] != undefined) {
        var alternated = stem.slice(0, i) + "ի" + stem.slice(i+1)
    } else if (stem[i] == 'ո' && stem[i+1] == 'յ' && stem[i+2] != undefined) {
        var alternated = stem.slice(0, i+1) + "ւ" + stem.slice(i+2)
    } else if (stem[i] == 'ո' && stem[i+1] == 'ւ' && stem[i+2] != undefined) {
        var alternated = stem.slice(0, i) + stem.slice(i+2)
    } else if (stem[i] == 'ի' && stem[i+1] != undefined) {
        var alternated = stem.slice(0, i) + stem.slice(i+1)
    } else if (stem[i] == 'է' && stem[i+1] != undefined) {
        var alternated = stem.slice(0, i) + "ի" + stem.slice(i+1)
    } else {
        alternated = stem
    }
}
alert(alternated)

It must change the stem‘s value in some conditions and not to change in others and give the changed/not changed value to alternated. But it doesn’t work, never change the stem, else statement works everytime. If I delete else statement everything works great. I tried to write it with switch, it had the same problem, didn’t work with default: and worked great without…