这个叫扩展运算符 https://dev.to/sagar/three-dots---in-javascript-26ci 5 种用法 1 functionmyFunc(...[x, y, z]) { return x * y* z; }myFunc(1)// NaNmyFunc(1,2,3)// 6myFunc(1,2,3,4)// 6 (fourth parameter is not destructured) 2 functionmyFunc(x, y, ...params) {// ...
There are multiple techniques available to determine the smallest and largest numbers in a JavaScript array, with varying performance based on the array's size. Math.max() can be used for regular arrays by employing three dots. For instance, the following example demonstrates how to find the ma...
步骤1:通过javascript中的three dots将所有数组合并到一个数组中。 步骤2:使用Array.reduce返回结果。 let array1 = [ { categoryName: "category 1" }, { categoryName: "category 2" }, { categoryName: "category 3" }, { categoryName: "category 4" }, ]; let array5 = [ { categoryName: "catego...
There's an easy way to distinguish between them: When three dots (…) is at the end of function parameters, it's "rest parameters" and gathers the rest of the list of arguments into an array. When three dots (…) occurs in a function call or alike, it's called a "spread operator...
可以把它想象成Array.prototype.concat的替代品. rest运算符 使用函数的参数时,无论是完全替换参数还是与函数的参数一起替换参数,这三个点也称为rest运算符。 当像这样使用它时,rest操作符使开发人员能够创建可以获取无限数量的参数的函数,也称为变量arity或可变函数。
Above,we don’t use the spread operator.By doing this, when the arr array is created, the middle array is inserted into the middle of the arr array as an array within an array. This is fine if that’s the goal, but what if we want only a single array?
Here, we defined an array with three values. While extracting the values, we use the "..." operator, which returns the array of the rest of the elements. Yes, you read it right. The rest of the variable will have the rest of the values in the form of an array. ...
Three Dots Rest Operator 在JavaScript 函数调用时我们往往会使用内置的 arguments 对象来获取函数的调用参数,不过这种方式却存在着很多的不方便性。譬如 arguments 对象是 Array-Like 对象,无法直接运用数组的 .map() 或者 .forEach() 函数;并且因为 arguments 是绑定于当前函数作用域,如果我们希望在嵌套函数里使用外...
同样,通过 new Array() 创建的对象的原型就是 Array.prototype,通过 new Date() 创建的对象的原型就是 Date.prototype。当第一次学习 JavaScript 时,这可能令人困惑。请记住:几乎所有对象都有原型,但只有相对较少的对象具有原型属性。正是这些具有原型属性的对象定义了所有其他对象的原型。
This operator is often used to create a shallow copy of an array. The spread operator consists of three dots, like an ellipsis (…). Let’s try to create a copy of our “berries” array from earlier: var berries = ["Strawberry", "Gooseberry", "Raspberry"]; var fruits = [......