Tutorial 3: Example 1

Primitive Types, typeof(), numbers, boolean, string, and arrays

<SCRIPT LANGUAGE="JavaScript">
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function func() {
}

document.writeln("<B>Primitive Types and typeof() built-in function</B>" + "<BR><BR>");

var changingVariable; // Must declare var changingVariable. If this line is deleted,
                                  // the next document.writeln("Undefined: will cause run-time error.

document.writeln("Undefined: changingVariable = " + changingVariable + ".<BR>");
document.writeln("Undefined: typeof(changingVariable) = " + typeof(changingVariable) + ".<BR><BR>");

changingVariable = "Hello World"; // String
document.writeln("String: changingVariable = " + changingVariable + ".<BR>");
document.writeln("String: typeof(changingVariable) = " + typeof(changingVariable) + ".<BR><BR>");

changingVariable = 8; // Integer
document.writeln("Integer: changingVariable = " + changingVariable + ".<BR>");
document.writeln("Integer: typeof(changingVariable) = " + typeof(changingVariable) + ".<BR><BR>");

changingVariable = 5.367; // Floating-point number
document.writeln("Floating-point number: changingVariable = " + changingVariable + ".<BR>");
document.writeln("Floating-point number: typeof(changingVariable) = " + typeof(changingVariable) + ".<BR><BR>");

changingVariable = true; // Boolean
document.writeln("Boolean: changingVariable = " + changingVariable + ".<BR>");
document.writeln("Boolean: typeof(changingVariable) = " + typeof(changingVariable) + ".<BR><BR>");

changingVariable = null; // null
document.writeln("null: changingVariable = " + changingVariable + ".<BR>");
document.writeln("null: typeof(changingVariable) = " + typeof(changingVariable) + ".<BR><BR>");

changingVariable = new Array; // Array
document.writeln("Array: changingVariable = " + changingVariable + ".<BR>");
document.writeln("Array: typeof(changingVariable) = " + typeof(changingVariable) + ".<BR><BR>");

document.writeln("Function: func = " + func + ".<BR>");
document.writeln("Function: typeof(func) = " + typeof(func) + ".<BR><BR>");


document.writeln("<BR><BR>");
document.writeln("<B>Numeric Data Types</B>" + "<BR><BR>");
document.writeln("The Largest representable number: Positive:" + "<BR>");
document.writeln("Number.MAX_VALUE=" + Number.MAX_VALUE + ".<BR>");
document.writeln("Number.MAX_VALUE+1=" + (Number.MAX_VALUE + 1) + ".<BR>");
document.writeln("Number.MAX_VALUE+1.0e291=" + (Number.MAX_VALUE + 1.0e291) + ".<BR>");
document.writeln("Number.MAX_VALUE+1.0e292=" + (Number.MAX_VALUE + 1.0e292) + ".<BR>");
document.writeln("Number.MAX_VALUE*10=" + (Number.MAX_VALUE * 10) + ".<BR><BR>");

document.writeln("The Largest representable number: Negative:" + "<BR>");
document.writeln("-Number.MAX_VALUE=" + (-Number.MAX_VALUE) + ".<BR>");
document.writeln("-Number.MAX_VALUE-1=" + (-Number.MAX_VALUE - 1) + ".<BR>");
document.writeln("-Number.MAX_VALUE-1.0e291=" + (-Number.MAX_VALUE - 1.0e291) + ".<BR>");
document.writeln("-Number.MAX_VALUE-1.0e292=" + (-Number.MAX_VALUE - 1.0e292) + ".<BR>");
document.writeln("(-Number.MAX_VALUE)*10=" + ((-Number.MAX_VALUE) * 10) + ".<BR><BR>");

document.writeln("The Smallest representable number:" + "<BR>");
document.writeln("Number.MIN_VALUE=" + Number.MIN_VALUE + ".<BR><BR>");

document.writeln("Number.NaN=" + Number.NaN + ".<BR>");
document.writeln("Number.NEGATIVE_INFINITY=" + Number.NEGATIVE_INFINITY + ".<BR>");
document.writeln("Number.POSITIVE_INFINITY=" + Number.POSITIVE_INFINITY + ".<BR>");

if ((-Number.MAX_VALUE - 1.0e292) == Number.NEGATIVE_INFINITY) {
    document.writeln("(-Number.MAX_VALUE - 1.0e292). Yes, NEGATIVE_INFINITY" + ".<BR>");
}
else {
    document.writeln("(-Number.MAX_VALUE - 1.0e292). No, NEGATIVE_INFINITY" + ".<BR>");
}

if ((Number.MAX_VALUE + 1.0e292) == Number.POSITIVE_INFINITY) {
    document.writeln("Number.MAX_VALUE + 1.0e292. Yes, POSITIVE_INFINITY" + ".<BR>");
}
else {
    document.writeln("Number.MAX_VALUE + 1.0e292. No, POSITIVE_INFINITY" + ".<BR>");
}

document.writeln("<BR><BR>");
document.writeln("<B>Boolean Values</B>" + "<BR><BR>");
var boolean_true = true; // case-sensitive: true, not TRUE or True
document.writeln("boolean_true=" + boolean_true + ".<BR>");
document.writeln("boolean_true + 1=" + (boolean_true + 1) + ".<BR>");
var boolean_false = false; // case-sensitive: false, not FALSE or False
document.writeln("boolean_false=" + boolean_false + ".<BR>");
document.writeln("boolean_false + 1=" + (boolean_false + 1) + ".<BR>");

document.writeln("<BR><BR>");
document.writeln("<B>Strings</B>" + "<BR><BR>");
document.writeln("This is a literal string" + ".<BR>");
document.writeln("This string contains a single 'quoted' string" + ".<BR>");
document.writeln('This string contains a double "quoted" string' + ".<BR><BR>");

document.writeln("<BR><BR>");
document.writeln("<B>Array</B>" + "<BR><BR>");
var array_var = new Array();
document.writeln("var array_var = new Array();" + ".<BR>");
document.writeln("array_var=" + array_var + ".<BR>");

var array_var = new Array(2);
document.writeln("var array_var = new Array(2);" + ".<BR>");
document.writeln("array_var=" + array_var + ".<BR>");
document.writeln("array_var[0]=" + array_var[0] + ".<BR>");
document.writeln("array_var[1]=" + array_var[1] + ".<BR>");
array_var[2] = "new_element";
document.writeln("array_var[2]=" + array_var[2] + ".<BR>");

var array_var = new Array(5, "text");
document.writeln("var array_var = new Array(5, \"text\");" + ".<BR>");
document.writeln("array_var=" + array_var + ".<BR>");
document.writeln("array_var[0]=" + array_var[0] + ".<BR>");
document.writeln("array_var[1]=" + array_var[1] + ".<BR>");

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Output: