add javascripts basic

JavaScriptBasics/if.js

@@ -0,0 +1,28 @@
+var price = 1000;
+
+/*
+if (price > 100) {   //true or false ---- Booloen
+    console.log ("You have 10% dicount for this item ");
+    console.log ("log again");
+}
+if (price === 100) {    //note the operator!
+    console.log ("You have 8% discunt for this item");
+}
+if (price === 50) {       //note the operator!
+    console.log ("Purchase for 100 or more to get discount")
+}
+*/
+
+
+
+if (price > 100) {
+    console.log ("You have 10% dicount for this item ");
+} else if (price === 100) {
+    console.log ("You have 8% discunt for this item");
+ } else if (price === 50) {
+    console.log ("Purchase for 100 or more to get discount");
+ } else {
+     console.log("invalid data");
+ }
+
+  

JavaScriptBasics/simpleloop.js

@@ -0,0 +1,21 @@
+/*
+for (var i=0; i<10; i=i+2) {         //i - loop control variable  
+  console.log(i);
+}
+*/
+
+
+for (i=0; i<10; i++){
+    for(j=0; j<5; j++){
+        console.log(j);
+    }
+}
+
+
+/*
+ var i = 0;
+ while (i<10){
+  console.log(i);
+  i++;      
+}
+*/

JavaScriptBasics/stringMethods.js

@@ -0,0 +1,19 @@
+//Some essential string object methods 
+var myStr = "I'm feeling great.";
+var l = myStr.length; 
+console.log("charater count:" + l);
+console.log(myStr[2]);   //m
+console.log(myStr[4]); //f
+
+var subStr1 = myStr.slice(4,11);  // returns starting position and up to (but not including) the ending position 
+var subStr2 =  myStr.slice(12); //returns part of the string from position 10
+console.log(subStr1);
+console.log(subStr2);
+var p1 = myStr.indexOf('feel');//returns 4, ie the substring is at pos 10
+var p2 = myStr.indexOf('test');// returns -1, which means not found 
+console.log(p1 + ", " +p2)
+
+console.log(myStr.replace('feel','game')) 
+console.log(myStr.toLowerCase());//convert entire string to lowercase
+console.log(myStr.toUpperCase());//convert entire string to uppercase
+

JavaScriptBasics/variables.js

@@ -0,0 +1,24 @@
+/* variables, numsbers, strings, mixed type operations, 
+template literals, Boolean, semicolon, LET/VAR, case-sensitive, comments */
+var a = 10;  //a is a name for memory location
+let b = 20.5;
+let givenName = "James"
+var lastName = 'LIM'
+var myText = "I'm feeling great.";
+a = 20;
+var c;
+console.log(c); //undefined!
+var d = null;
+//console.log(D);  //JS is case sensitive
+console.log(d);
+c = a+b;
+d = a + lastName
+const e= 10;  //constant
+//e = a+b;
+let f = e < b;
+let g = f + 1;
+console.log(`Hello ${givenName}`);  //
+console.log("Hello " + givenName); 
+console.log(`value of a is ${a}, value of b is ${b}, value of c is ${c}, value of d is ${d}, value of e is ${e}`);
+console.log(`value of f is ${f}, value of g is ${g}`);
+console.log("I'm " + givenName + " " + lastName + ". " + myText);

playground/variables.js

@@ -9,7 +9,8 @@ var d = 55;
 // template literal `..`
 console.log(`My answer is ${d}`);
 
-var myStr = 'Hello World';
+var myStr = "Hello \" World";
+console.log(myStr);
 
 var x = 10;
 var y = 20;