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48 lines
2.1 KiB
JavaScript
48 lines
2.1 KiB
JavaScript
var s1 = new String("Hello !");
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var s2 = new String("Hello !");
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s1 == s2; // Is false, because they are two distinct objects.
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s1.valueOf() == s2.valueOf(); // Is true.
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//Automatic type coercion
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f1(true == 2 ); // false... true → 1 !== 2 ← 2
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alert2(false == 2 ); // false... false → 0 !== 2 ← 2
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alert3(true == 1 ); // true.... true → 1 === 1 ← 1
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alert4(false == 0 ); // true.... false → 0 === 0 ← 0
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alert5(true == "2"); // false... true → 1 !== 2 ← "2"
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alert6(false == "2"); // false... false → 0 !== 2 ← "2"
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alert7(true == "1"); // true.... true → 1 === 1 ← "1"
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alert8(false == "0"); // true.... false → 0 === 0 ← "0"
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alert9(false == "" ); // true.... false → 0 === 0 ← ""
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alert(false == NaN); // false... false → 0 !== NaN
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//Type checked comparison (no conversion of types and values)
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alert(true === 1); // false... data types do not match
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//Explicit type coercion
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alert(true === !!2); // true.... data types and values match
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alert(true === !!0); // false... data types match but values differ
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alert( 1 ? true : false); // true.... only ±0 and NaN are “falsy” numbers
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alert("0" ? true : false); // true.... only the empty string is “falsy”
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alert(Boolean({})); // true.... all objects are “truthy” except null
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var d = new Date(2010, 2, 1, 14, 25, 30); // 2010-Mar-01 14:25:30
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// Displays '2010-3-1 14:25:30':
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alert(d.getFullYear() + '-' + (d.getMonth()+1) + '-' + d.getDate() + ' '
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+ d.getHours() + ':' + d.getMinutes() + ':' + d.getSeconds());
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// Built-in toString returns something like 'Mon Mar 01 2010 14:25:30 GMT-0500 (EST)':
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alert(d);
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s.length
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var myRe = /(\d{4}-\d{2}-\d{2}) (\d{2}:\d{2}:\d{2})/;
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var results = myRe.exec("The date and time are 2009-09-08 09:37:08.");
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if (results) {
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alert("Matched: " + results[0]); // Entire match
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var my_date = results[1]; // First group == "2009-09-08"
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var my_time = results[2]; // Second group == "09:37:08"
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alert("It is " + my_time + " on " + my_date);
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} else alert("Did not find a valid date!");
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try
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