letp = {x:2.3,y: -1.2};// An object with 2 propertiesletq = {};// An empty object with no propertiesq.x=2.3; q.y= -1.2;// Now q has the same properties as p 在ES6 中,对象文字具有更丰富的语法(详细信息请参见§6.10)。对象文字可以嵌套。例如: letrectangle = {upperLeft: {x:...
"1" + 2 // => "12": concatenation after number-to-string 1 + {} // => "1[object Object]": concatenation after object-to-string true + true // => 2: addition after boolean-to-number 2 + null // => 2: addition after null converts to 0 2 + undefined // => NaN: additio...
1 + 2 // => 3: addition. "1" + "2" // => "12": concatenation. "1" + 2 // => "12": 2 is converted to "2". 11 < 3 // => false: numeric comparison. "11" < "3" // => true: string comparison. "11" < 3 // => false: numeric comparison, "11" converted to ...
// Values can be assigned to variables with an = sign x = 0; // Now the variable x has the value 0 x // => 0: A variable evaluates to its value. // JavaScript supports several types of values x = 1; // Numbers. x = 0.01; // Numbers can be integers or reals. x = "he...
// Values can be assigned to variables with an = sign x = 0; // Now the variable x has the value 0 x // => 0: A variable evaluates to its value. // JavaScript supports several types of values x = 1; // Numbers. x = 0.01; // Numbers can be integers or reals. x = "...
letvalue1=10letvalue2=5letsum=value1+value2// addition of valuesconsole.log(sum); We need multiple number values assigned or values provided by the user to perform the addition operation. In the below example, we’ll get two values from user input and perform an addition operation, then ...
JavaScript Addition TheAddition Operator(+) adds numbers: Adding letx =5; lety =2; letz = x + y; Try it Yourself » JavaScript Multiplication TheMultiplication Operator(*) multiplies numbers: Multiplying letx =5; lety =2; letz = x * y; ...
JavaScript objects, variables, properties, and methods can beundefined. In addition, empty JavaScript objects can have the valuenull. This can make it a little bit difficult to test if an object is empty. You can test if an object exists by testing if the type isundefined: ...
第2题 [typeof null, null instanceof Object] 两个知识点: Operators/typeof Operators/instanceof Operators/instanceof(中) typeof 返回一个表示类型的字符串. instanceof 运算符用来检测 constructor.prototype 是否存在于参数 object 的原型链上. 这个题可以直接看链接... 因为 typeof null === 'object' ...
Addition (Concatenation) of 2 Strings with space between them Addition of 2 Numbers, among them one is in the String format Only for the 'Addition Operation', the problem of 'Concat' will happen. For 'Subtraction/Multiplication/Division Operation', this problem of 'Concat' will not happen....