comments | Javascript source | Execution result in your current browser |
all integer or floating numbers are same, they represented as 64-bit floating point numbers | var int1=15;
var hex1=0xF;
var long1=15;
var float1=15.0;
document.write("int1 typeof="+typeof(int1)+" value="+int1);
document.write("<br/>hex1 typeof="+typeof(hex1)+" value="+hex1);
document.write("<br/>long1 typeof="+typeof(long1)+" value="+long1);
document.write("<br/>float1 typeof="+typeof(float1)+" value="+float1);
document.write("<br/>int1===hex1? "+(int1===hex1));
document.write("<br/>hex1===long1? "+(hex1===long1));
document.write("<br/>float1===long1? "+(long1===float1));
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nubmer constants | var constants=["Number.MAX_VALUE", "Number.MIN_VALUE",
"Infinity",
"Number.POSITIVE_INFINITY", "Number.NEGATIVE_INFINITY",
"NaN", "Number.NaN"
];
for (var i=0; i<constants.length; i++) {
var name=constants[i];
document.write(
"<br/>"+name+"= "+eval(name)
);
}
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String and Char are all "string" | var StringExamples=["Hello", 'Hello',
"'Are you ok', he said.", '"I am ok"',
"", "Line1\nLine1", ''
];
for (var i=0; i<StringExamples.length; i++) {
var stringValue=StringExamples[i];
document.write(
"<br/>"+stringValue
);
}
document.write( ("Hello" === 'Hello'));
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boolean | var b1=1 === 1;
var true1=true; //True or TRUE are not valid constant
var false1=false;
document.write(typeof(b1)+" "+b1);
document.write("<br/> constant true="+typeof(true1)+" "+true1);
document.write("<br/> constant false="+typeof(false1)+" "+false1);
document.write("<br/> true===b1?"+(true1===b1));
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undefined is not a keyword and is a global variable | var b;
document.write(
"uninitialized variable: typeof="+typeof(b)+", value="+b);
document.write("<br/>compare with two undefined variable: "+ (undefined===b)); //test if a variable is ever initialized
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null is the language keyword and it is a special object | document.write("null typeof is: "+typeof(null));
document.write("<br/>the value of null: "+null);
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