[總結] Javascript Boolean運算值測試

測試指令碼

<script type="text/javascript">  <!--var _boolean_true = true;var _boolean_false = false;var _undefined;var _null = null;var _int = 10000;var _int_1 = 1;var _int_0 = 0;var _int__0 = -0;var _NaN = NaN;var _string_onestring = "onestring";var _string_empty = "";var _string_1 = "1";var _string_0 = "0";var _string_true = "true";var _string_false = "false";var _string_null = "null";var _string_undefined = "undefined";var _function = function() {};var _array_empty = [];var _array_notempty = [1,2];var _object_empty = {};var _object_notempty = {name:'yourname'};println("Boolean(_boolean_true) : " + Boolean(_boolean_true));println("Boolean(_boolean_false) : " + Boolean(_boolean_false));println("Boolean(_undefined) : " + Boolean(_undefined));println("Boolean(_null) : " + Boolean(_null));println("Boolean(_int) : " + Boolean(_int));println("Boolean(_int_1) : " + Boolean(_int_1));println("Boolean(_int_0) : " + Boolean(_int_0));println("Boolean(_int__0) : " + Boolean(_int__0));println("Boolean(_NaN) : " + Boolean(_NaN));println("Boolean(_string_onestring) : " + Boolean(_string_onestring));println("Boolean(_string_empty) : " + Boolean(_string_empty));println("Boolean(_string_1) : " + Boolean(_string_1));println("Boolean(_string_0) : " + Boolean(_string_0));println("Boolean(_string_true) : " + Boolean(_string_true));println("Boolean(_string_false) : " + Boolean(_string_false));println("Boolean(_string_null) : " + Boolean(_string_null));println("Boolean(_function) : " + Boolean(_function));println("Boolean(_array_empty) : " + Boolean(_array_empty));println("Boolean(_array_notempty) : " + Boolean(_array_notempty));println("Boolean(_object_empty) : " + Boolean(_object_empty));println("Boolean(_object_notempty) : " + Boolean(_object_notempty));println();println("!_boolean_true : " + !_boolean_true);println("!_boolean_false : " + !_boolean_false);println("!_undefined : " + !_undefined);println("!_null : " + !_null);println("!_int : " + !_int);println("!_int_1 : " + !_int_1);println("!_int_0 : " + !_int_0);println("!_int__0 : " + !_int__0);println("!_NaN : " + !_NaN);println("!_string_onestring : " + !_string_onestring);println("!_string_empty : " + !_string_empty);println("!_string_1 : " + !_string_1);println("!_string_0 : " + !_string_0);println("!_string_true : " + !_string_true);println("!_string_false : " + !_string_false);println("!_string_null : " + !_string_null);println("!_function : " + !_function);println("!_array_empty : " + !_array_empty);println("!_array_notempty : " + !_array_notempty);println("!_object_empty : " + !_object_empty);println("!_object_notempty : " + !_object_notempty);println();println("!!_boolean_true : " + !!_boolean_true);println("!!_boolean_false : " + !!_boolean_false);println("!!_undefined : " + !!_undefined);println("!!_null : " + !!_null);println("!!_int : " + !!_int);println("!!_int_1 : " + !!_int_1);println("!!_int_0 : " + !!_int_0);println("!!_int__0 : " + !!_int__0);println("!!_NaN : " + !!_NaN);println("!!_string_onestring : " + !!_string_onestring);println("!!_string_empty : " + !!_string_empty);println("!!_string_1 : " + !!_string_1);println("!!_string_0 : " + !!_string_0);println("!!_string_true : " + !!_string_true);println("!!_string_false : " + !!_string_false);println("!!_string_null : " + !!_string_null);println("!!_function : " + !!_function);println("!!_array_empty : " + !!_array_empty);println("!!_array_notempty : " + !!_array_notempty);println("!!_object_empty : " + !!_object_empty);println("!!_object_notempty : " + !!_object_notempty);function println(s) { s = s || ""; document.writeln(s + "<br/>"); }  //--></script>

運行指令碼

測試結果

Boolean(_boolean_true) : true
Boolean(_boolean_false) : false
Boolean(_undefined) : false
Boolean(_null) : false
Boolean(_int) : true
Boolean(_int_1) : true
Boolean(_int_0) : false
Boolean(_int__0) : false
Boolean(_NaN) : false
Boolean(_string_onestring) : true
Boolean(_string_empty) : false
Boolean(_string_1) : true
Boolean(_string_0) : true
Boolean(_string_true) : true
Boolean(_string_false) : true
Boolean(_string_null) : true
Boolean(_function) : true
Boolean(_array_empty) : true
Boolean(_array_notempty) : true
Boolean(_object_empty) : true
Boolean(_object_notempty) : true

!_boolean_true : false
!_boolean_false : true
!_undefined : true
!_null : true
!_int : false
!_int_1 : false
!_int_0 : true
!_int__0 : true
!_NaN : true
!_string_onestring : false
!_string_empty : true
!_string_1 : false
!_string_0 : false
!_string_true : false
!_string_false : false
!_string_null : false
!_function : false
!_array_empty : false
!_array_notempty : false
!_object_empty : false
!_object_notempty : false

!!_boolean_true : true
!!_boolean_false : false
!!_undefined : false
!!_null : false
!!_int : true
!!_int_1 : true
!!_int_0 : false
!!_int__0 : false
!!_NaN : false
!!_string_onestring : true
!!_string_empty : false
!!_string_1 : true
!!_string_0 : true
!!_string_true : true
!!_string_false : true
!!_string_null : true
!!_function : true
!!_array_empty : true
!!_array_notempty : true
!!_object_empty : true
!!_object_notempty : true

結論

0、-0、null、""、false、undefined 或 NaN：此7種結果經過Boolean運算後結果false，其他情況為true。