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1. BooleanÖµ¡¢Êý×Ö¡¢×Ö·û´®µÄÔʼֵÊÇα¶ÔÏó£¬ÕâÒâζ×ÅËûÃǾßÓÐÊôÐԺͷ½·¨¡£
var test = "hello";
alert(test.length); //outputs "5"
2. javascript Ëù¶¨ÒåµÄËùÓжÔÏó¶¼ÓÐ toString() ·½·¨£¬²»¹ÜÊÇα¶ÔÏó»¹ÊÇÕæµÄ¶ÔÏó£¬Boolean µÄ toString() ·½·¨Ö»·µ»Ø “true” »òÕß“false”¡£
var test = false;
alert(test.toString()); //outputs "false"
3. parseInt() ºÍ parseFloat()
alert(parseInt("1234test")); //outputs "1234"
alert(parseInt("0xA")); //outputs "10"
alert(parseInt("22.1")); //outputs "22"
alert(parseInt("test")); //outputs "NaN"
4. String() ºÍ toString() ΨһµÄÇø±ðÔÚÓÚ¶Ô null »òÕß undefined ÖµµÄÇ¿ÖÆ×ª»»ÉÏ¡£
var test = String(null) //"null"
var test1 = null;
var test2 = test1.toString(); //»á²úÉú´íÎó
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