Determine if JavaScript value is an integer

Question

Possible Duplicate    Check if a variable contains a numerical value in Javascript        How do I check if variable is an integer in jQuery   Example    if  id    int       Do this     Im using the following to get the ID from the URL   var id     getURLParam  id      But I want to check if the variable is an integer

User · Answer

Use jQuery s IsNumeric method   http   api jquery com jQuery isNumeric   if    isNumeric id          it s numeric     CORRECTION  that would not ensure an integer   This would   if    id     match    d              it s all digits     That  of course  doesn t use jQuery  but I assume jQuery isn t actually mandatory as long as the solution works

User · Answer

Here s a polyfill for the Number predicate functions    use strict    Number isNaN   Number isNaN        n   gt  n     n     only NaN  Number isNumeric   Number isNumeric        n   gt  n      n     all numbers excluding NaN  Number isFinite   Number isFinite        n   gt  n      n                  all numbers excluding NaN        amp  amp  n  gt   Number MIN VALUE     and -Infinity        amp  amp  n  lt   Number MAX VALUE     and  Infinity  Number isInteger   Number isInteger        n   gt  n      n                 all numbers excluding NaN        amp  amp  n  gt   Number MIN VALUE    and -Infinity        amp  amp  n  lt   Number MAX VALUE    and  Infinity        amp  amp    n   1                  and non-whole numbers  Number isSafeInteger   Number isSafeInteger        n   gt  n      n                        all numbers excluding NaN        amp  amp  n  gt   Number MIN SAFE INTEGER    and small unsafe numbers        amp  amp  n  lt   Number MAX SAFE INTEGER    and big unsafe numbers        amp  amp    n   1                         and non-whole numbers   All major browsers support these functions  except isNumeric  which is not in the specification because I made it up  Hence  you can reduce the size of this polyfill    use strict    Number isNumeric   Number isNumeric        n   gt  n      n     all numbers excluding NaN   Alternatively  just inline the expression n      n manually

User · Answer

Try this   if Math floor id     id  amp  amp    isNumeric id      alert  yes its an int         isNumeric id  checks whether it s numeric or not Math floor id     id will then determine if it s really in integer value and not a float  If it s a float parsing it to int will give a different result than the original value  If it s int both will be the same

[javascript] Determine if JavaScript value is an "integer"?

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