test.html

<script src="src/strings.js"></script>
<script>
var test = "Hello world!";
var testNum = "12,345,679.312";
var testTags = "<span style='color:red'><i>Hello</i> <b>world</b>!</span>";
var testSentence = "The quick brown fox jumps over the lazy dog";
var testTitle = "new rules grant F.B.I., DEA & CIA access to 'raw' NSA surveillance data";

var a = strings.count(test, "l"); // 3
console.log(a);

var b0 = strings.endsWith(test, "D!"); // false
var b1 = strings.endsWith(test, "D!", false); // false
var b2 = strings.endsWith(test, "D!", true); // true
console.log(b0, b1, b2);

var c0 = strings.includes("Hello world", "WO"); // false
var c1 = strings.includes("Hello world", "WO", true); // true
var c2 = strings.includes("Hello world", "WO", false); // false
console.log(c0, c1, c2);

var d0 = strings.isAllCaps("YOOOO"); // true
var d1 = strings.isAllCaps("YO!"); // true
var d2 = strings.isAllCaps("YoO!"); // false
console.log(d0, d1, d2);

var e0 = strings.isAllDigits(testNum); // false;
var e1 = strings.isAllDigits(strings.removeAll(testNum, ",")); // false
var e2 = strings.isAllDigits(strings.removeAll(testNum, ",").replace(".", "")); // true
console.log(e0, e1, e2);

var f0 = strings.isAllLower(test); // false
var f1 = strings.isAllLower(test.toLowerCase() + "3"); // true
console.log(f0, f1);

var g = strings.keepAll(test, "l"); // "lll"
console.log(g);

var ga = strings.keepEnd(test, 3); // "ld!"
console.log(ga);

var h0 = strings.keepOne(test, "l"); // "l"
var h1 = strings.keepOne(test, "z"); // ""
console.log(h0, h1);

var i = strings.keepStart(test, 3); // "Hel"
console.log(i);

var j = strings.numberCommas(1234123.234); // "1,234,123.234"
console.log(j);

var k0 = strings.numberDecimals(1234123.2134, 2); // "1234123.21" 
var k1 = strings.numberDecimals(1234123, 2); // "1234123.00"
console.log(k0, k1);

var l = strings.numberLakhs(1345122345.235); // "1,34,51,22,345.235"
console.log(l);

var m0 = strings.numberPrependZeros(1234, 4); // "1234"
var m1 = strings.numberPrependZeros(123, 4); // "0123"
var m2 = strings.numberPrependZeros(12345, 4); // "12345"
var m3 = strings.numberPrependZeros(1, 4); // "0001"
var m4 = strings.numberPrependZeros("", 4); // "0000"
var m5 = strings.numberPrependZeros("red", 4); // "0red"
console.log(m0, m1, m2, m3, m4, m5);

var n0 = strings.removeAll("Hello Jill how are you lady?", "l"); // "Heo Ji how are you ady?"
var n1 = strings.removeAll("Hello Jill how are you lady?", "ll"); // "Heo Ji how are you lady?"
console.log(n0, n1);

var o = strings.removeDigits(testNum); // ",,."
console.log(o);

var p = strings.removeFirst(test, "l"); // "Helo world!"
console.log(p);

var q = strings.removeLast(test, "l"); // "Hello word!"
console.log(q);

var r = strings.removeSymbols(test); // "Hello world"
console.log(r);

var s0 = strings.removeTags(testTags); // "Hello world!"
var s1 = strings.removeTags(testTags, ["i"]); // <i>Hello</i> world!
console.log(s0, s1);

var t = strings.replaceAll(test, "l", "z"); // "Hezzo worzd!"
console.log(t);

var ta = strings.replaceAt(test, 6, "Jonny"); // Hello Jonny!
console.log(ta);

var u = strings.replaceFirst(test, "l", "z"); // "Hezlo world!"
console.log(u);

var v = strings.replaceLast(test, "l", "z"); // "Hello worzd!"
console.log(v);

var w = strings.reverseCharacters(test); // "!dlrow olleH"
console.log(w);

var x = strings.reverseWords(test); // "world! Hello"
console.log(x);

var y = strings.shuffleCharacters(test); // e.g. "!oloHw elrld"
console.log(y);

var z = strings.shuffleCharactersInWords(test); // e.g. "oeHll !lrwdo"
console.log(z);

var aa = strings.shuffleWords(testSentence); // e.g. "over The lazy the quick fox jumps dog brown"
console.log(aa);

var ab0 = strings.startsWith("Hello world", "he"); // false
var ab1 = strings.startsWith("Hello world", "he", true); // true
var ab2 = strings.startsWith("Hello world", "he", false); // false
console.log(ab0, ab1, ab2);

var ac = strings.toCamelCase(test); // "helloWorld"
console.log(ac);

var ad = strings.toSentenceCase(testTitle); // "New rules grant F.B.I., DEA & CIA access to raw NSA surveillance data"
console.log(ad);

var ae = strings.toSlugCase(test); // "hello-world"
console.log(ae);

var af = strings.toSnakeCase(test); // "hello_world"
console.log(af);

var ag = strings.toStartCase(test); // "Hello World!"
console.log(ag);

var ah0 = strings.toTitleCase("the quick brown fox jumps over the lazy dog"); // "The Quick Brown Fox Jumps Over the Lazy Dog"
var ah1 = strings.toTitleCase("javascript: a beginner's guide to the language of the web"); // "Javascript: A Beginner's Guide to the Language of the Web"
var ah2 = strings.toTitleCase("james comey to remain on as FBI director"); // "James Comey to Remain on as FBI Director"
var ah3 = strings.toTitleCase(testTitle); // "New Rules Grant F.B.I., DEA & CIA Access to Raw NSA Surveillance Data"
console.log(ah0);
console.log(ah1);
console.log(ah2);
console.log(ah3);

</script>