最先触发var m = "大余",go对象:{m:undefined} => {m:"大余"} 然后执行foo()函数,创造出一个AO对象(执行上下文),此时还处于编译状态,AO对象:{m:undefined},注意了,这个时候查找顺序是从自身开始查找,自身没有才去父级查找,而大余这个变量信息是在foo()的父级作用域中,所以之后才会去查找。此时执行上下文...
7-7.js const twoArray = ["One", "Two"]; const threeArray = Object.assign([...twoArray], {2:"Three"}); console,log(threeArray); //returns (3) ["One", "Two", "Three"] Listing 7-7Returning a Copy of an Array So Data Is Not Mutated 在本例中,第一行创建了一个数组。第二...
JAVASCRIPT NAMING CONVENTIONS: VARIABLES(变量) JavaScript variables are case sensitive. Therefore, JavaScript variables with lowercase and uppercase characters are different: JavaScript 变量命名是大小写敏感的。由于大小写敏感,以大写形式和小写形式命名的 JavaScript 变量,是完全不同的变量: var name = 'Robin ...
“A leading decimal point can be confused with a dot: ‘.{a}’.”:“‘{a}’前的点容易混淆成小数点”, “Use the array literal notation [].”:“使用数组的符号 []“, “Expected an operator and instead saw ‘{a}’.”:“需要用一个符号来代替’{a}’”, “Unexpected space after ‘{...
Because of this, you can have variables of different types in the same Array. You can have objects in an Array. You can have functions in an Array. You can have arrays in an Array: myArray[0] = Date.now; myArray[1] = myFunction; ...
“Use the array literal notation [].”:“使用数组的符号 []“, “Expected an operator and instead saw ‘{a}’.”:“需要用一个符号来代替’{a}’”, “Unexpected space after ‘{a}’.”:“在’{a}’之后不能出现空格”, “Unexpected space before ‘{a}’.”:“在’{a}’之前不能出现空...
要在字符串中插入反斜杠字面量,必须转义反斜杠。例如,要把文件路径赋值给一个字符串,可以采用如下方式: js consthome="c:\\temp"; 也可以在换行之前加上反斜杠以转义换行。这样反斜杠和换行都不会出现在字符串的值中。 js conststr="this string \ is broken \ across multiple \ lines.";console.log(str...
“Use the array literal notation [].”:“使用数组的符号 []“, “Expected an operator and instead saw ‘{a}’.”:“需要用一个符号来代替’{a}’”, “Unexpected space after ‘{a}’.”:“在’{a}’之后不能出现空格”, “Unexpected space before ‘{a}’.”:“在’{a}’之前不能出现空...
function map(f, a) { const result = new Array(a.length); for (let i = 0; i < a.length; i++) { result[i] = f(a[i]); } return result; } 在以下代码中,该函数接收由函数表达式定义的函数,并对作为第二个参数接收的数组的每个元素执行该函数: jsCopy to Clipboard function map(f,...
ArrayPattern: an array pattern, for example, the left-hand side of [x, y] = arr ObjectPattern: an object pattern, for example, the left-hand side of {x, y: z} = o Here is an example of a query to find declaration statements that declare the same variable more than once, excludin...