z==null || z==""可以替换为!Boolean(z)或!z z!=null || z!=""可以替换为Boolean(z)或!!...
当作为一个构造函数(带有运算符 new)调用时,Boolean() 将把它的参数转换成一个布尔值,并且返回一个包含该值的 Boolean 对象。 如果作为一个函数(不带有运算符 new)调用时,Boolean() 只将把它的参数转换成一个原始的布尔值,并且返回这个值,如果省略 value 参数,或者设置为0、-0、null、""、false、undefined...
JSON does not allow trailing commas. JSON: person = {"firstName":"John","lastName":"Doe","age":46} JSON: points = [40,100,1,5,25,10]; Undefined is Not Null JavaScript objects, variables, properties, and methods can beundefined. ...
在JS的字符串里对[TAB]的表述是 /x09 你可以做这样的测试: alert(“/x41”); //看看得到是什么?? 是字母A(41是十六进制的ASCII码值) 我喜欢用 /x0f 这类的做分隔符, [TAB]键用户还是有可能输入的, 但 /x0f 就绝对不可能输入 var s = “A/x0fB/x0fC/x0fD/x0fE/x0fF/x0fG”; alert(s...
move This is the default tool for graphics with a point geometry that do not use a 3D object symbol layer. It should be used for specific cases where you just want to move selected polygon and polyline graphics without additional options. Additionally, the move tool does not support toggli...
the different additional primitive data type values that is null and undefined both are specified with no values are assigned to the variables it has their own special meanings we can assign the null to the variable it denotes the variables it does not have any values but it will have later...
a != b (check if a does not equal b) a <= b (check if a is less than or equal to b) a >= b (check if a is greater than or equal to b) # Strings a + b (string concatenation) a * num (repeat string <num> times) ...
This is because a node.js application does not have a browser interface that can display the Genesys Cloud login window.Optional parameters may be specified in the optional third parameter for loginPKCEGrant. This parameter accepts an object with key/value pairs. Supported properties:...
spatial references. You can switch between those basemaps in your application, and the view's spatial reference will automatically update. To opt out of this, set theMapView.spatialReferenceLockedproperty totrue- this will disable any basemaps with a spatial reference that does not match the Map...
describe('Array', function() { describe('#indexOf()', function() { it('should return -1 when the value is not present', function() { [1, 2, 3].indexOf(5).should.equal(-1); [1, 2, 3].indexOf(0).should.equal(-1); }); }); }); ...