03-使用数据

var pens;
pens = ["red", "blue", "green", "orange"];

console.log("Before: ", pens);

// PROPERTIES:
// Get a property of an object by name:
console.log("Array length: ", pens.length);

// METHODS:
// Reverse the array:
// pens.reverse();

// Remove the first value of the array:
// pens.shift();

// Add comma-separated list of values to the front of the array:
// pens.unshift("purple", "black");

// Remove the last value of the array:
// pens.pop();

// Add comma-separated list of values to the end of the array:
// pens.push("pink", "prussian blue");

// Find the specified position (pos) and remove n number of items from the array. Arguments: pens.splice(pos,n):
// pens.splice(pos, n) // Starts at the seccond item and removes two items.

console.log("After: ", pens);

// Create a copy of an array. Typically assigned to a new variable:
// var newPens = pens.slice();
// console.log("New pens: ", newPens);

// Return the first element that matches the search parameter after the specified index position. Defaults to index position 0. Arguments: pens.indexOf(search, index):
// var result = pens.indexOf(search, index);
// console.log("The search result index is: ", result);

// Return the items in an array as a comma separated string. The separator argument can be used to change the comma to something else. Arguments: pens.join(separator):
var arrayString = pens.join(" - ");
console.log("String from array: ", arrayString);

// MDN documentation for Array:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array

var date = new Date();
document.body.innerHTML = "<h1>Today is: " + date + "</h1>";


var a = 5;
var b = 4;
var sum = a + b;



var negInteger = -3.14159265359;
var escQuote = "Quotes can also be \"escaped\".";
var theSunIsWarm = true;
var emptyInside = null;
var justAnotherVariable;

// Try this in your console:
console.log(typeof insertVariableName);


var a = 5;
var b = 5;
var theNumbersMatch

if ( a == b ) {
    theNumbersMatch = true;
} else {
    theNumbersMatch = false;
}

console.log(theNumbersMatch);