Cuts a substring from a string based on a leading/trailing string

cutSubstr.js

/*
	Example - https://codepen.io/skoshy/pen/jmLyRm
  
  leading = string, or blank string '' which signifies first character
	trailing, string, or blank string '' which signifies last character
*/
function cutSubstr(string, leading, trailing) {
	let substr = '';
	
	// first, let's get the primary index
	let index1 = string.indexOf(leading);
	if (index1 == -1) {
		return false;
	} else {
		index1 += leading.length;
	}
	
	// secondary index
	let index2;
	if (trailing == '') {
		// if given an empty string, just go till the end of the string
		index2 = string.length;
	} else {
		index2 = string.indexOf(trailing, index1);
		if (index2 == -1) {
			return false;
		}
	}
	
	return string.substring(index1, index2);
}