I think I misunderstood what you want to achieve. Do you want to test if the string has any numbers in it and any "text" (ie, letters)?
If that's what you're after it would require using Regular Expressions, as mentioned above.
Try this code:
var v = this.getField("01_pallet_2_test").valueAsString;
var numbersRegExp = new RegExp("\\d", "g");
var lettersRegExp = new RegExp("[a-z]", "gi");
if (v=="") {
event.value = "";
} else if (numbersRegExp.test(v) && lettersRegExp.test(v)) {
event.value = "number with text";
} else if (numbersRegExp.test(v) && !lettersRegExp.test(v)) {
event.value = "only number";
} else if (!numbersRegExp.test(v) && lettersRegExp.test(v)) {
event.value = "only text";
} else if (!numbersRegExp.test(v) && !lettersRegExp.test(v)) {
event.value = "Other";
}