javascript 权威指南 学习笔记2: Comparison Operators

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< operator, the string "Zoo" is less than the string "aardvark".

Converting Strings to Numbers

var number = Number(string_value);var number = string_value - 0;

parseInt("3 blind mice");    // Returns 3parseFloat("3.14 meters");   // Returns 3.14parseInt("12.34");           // Returns 12parseInt("0xFF");            // Returns 255 

parseInt( ) can even take a second argument specifying the radix (base) of the number to be parsed. Legal values are between 2 and 36. For example:

parseInt("11", 2);           // Returns 3 (1*2 + 1)parseInt("ff", 16);          // Returns 255 (15*16 + 15)parseInt("zz", 36);          // Returns 1295 (35*36 + 35)parseInt("077", 8);          // Returns 63 (7*8 + 7)parseInt("077", 10);         // Returns 77 (7*10 + 7) 

If parseInt( ) or parseFloat( ) cannot convert the specified string to a number, it returns NaN:

parseInt("eleven");          // Returns NaNparseFloat("$72.47");        // Returns NaN

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