What should we use to convert a string to an integer? parseInt or Number?

parseInt and Number are semantically different, the Number constructor called as a function perform type conversion, but parseInt perform parseing.

Example:

// type conversion
Number("20px");       // NaN
Number("2e1");        // 20, exponential notation
 
// parsing:
parseInt("20px");       // 20
parseInt("10100", 2);   // 20
parseInt("2e1");        // 2

Keep in mind that bothparseInt and Number ignore the leading zero on the string, it will parse the number in decimal base, this is the standard on ECMAScript 5. In addition, parseInt will ignore trailing characters that don't correspond with any digit of the currently used base.

Number("010");         // 10
parseInt("0010");      // 10, decimal
parseInt("0010", 10);   // 10, decimal radix used
parseInt("0010e");      // 10, ignore trailing char that don't correspond with currently used base

Both parseInt and Number can handle numbers in hexadecimal notation:

Number("0xF");    // 15
parseInt("0xF");  //15