Things to pay attention to during javascript development

1. Define var
          Octal number (starting with 0). 0xAB: Hexadecimal number (starting with 0X) 3.14e7: Scientific notation (3.14 times 10 raised to the seventh power) 3.14-e7 (3.14 divided by 10 raised to the seventh power)
2.parInt( ) Things to note when converting strings to numbers.
If string starts with "0x", parseInt() will parse the rest of string into hexadecimal integers. If a string begins with 0, ECMAScript v3 allows an implementation of parseInt() to parse the following characters as octal or hexadecimal digits. If string starts with a number from 1 to 9, parseInt() will parse it into a decimal integer.
3. Determine whether it is a non-numeric value.
isNaN(x) x is required. The value to detect.
4. Determine whether the string is empty
                                                                                                                                                                                                                                      trim();
6.firebug
Console.log();
7.javascript does not have block-level scope.

1. Define var

          Octal number (starting with 0). 0xAB: Hexadecimal number (starting with 0X) 3.14e7: Scientific notation (3.14 times 10 raised to the seventh power) 3.14-e7 (3.14 divided by 10 raised to the seventh power)

2.parInt( ) Things to note when converting strings to numbers.
If string starts with "0x", parseInt() will parse the rest of string into hexadecimal integers. If a string begins with 0, ECMAScript v3 allows an implementation of parseInt() to parse the following characters as octal or hexadecimal digits. If string starts with a number from 1 to 9, parseInt() will parse it into a decimal integer.
3. Determine whether it is a non-numeric value.
isNaN(x) x is required. The value to detect.
4. Determine whether the string is empty
                                                                                                                                                                                                                                      trim();
6.firebug
Console.log();
7.javascript does not have block-level scope.

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