一.数组Array常用方法 1. 使用reduce const arr = [{ "code": "badge", "priceList": [{ "amount": 3000 }] }, { "code": "DigitalPhoto", "priceList": [{ "amount": 1990 }] } ] let arr2 = arr.reduce((pre, cur) => { pre[cur.code] = cur.priceList return pre }, {}) con...
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console.log(ary2.next());//Object {value: Array[2], done: false} value:Array[2] ---[0:0,1:1]; console.log(ary2.next());//Object {value: Array[2], done: false} value:Array[2] ---[0:1,1:2]; //可以看出每次执行这个next().都会返回一个该数组的索引和值组成的新的数组,被...
console.log(arrMap) //打印结果:['aaa','bbb','ccc'] 3. 使用filter(过滤) let arrFilter = [{ name: 'aaa', age: 23, address: 'henan' }, { name: 'bbbb', age: 26, address: 'hebei' }, { name: 'cccc', age: 27, address: 'anhui' }] arrFilter = arrFilter.filter(obj => ...
jsCopy to Clipboard filter(callbackFn) filter(callbackFn, thisArg) 参数 callbackFn 为数组中的每个元素执行的函数。它应该返回一个真值以将元素保留在结果数组中,否则返回一个假值。该函数被调用时将传入以下参数: element 数组中当前正在处理的元素。 index 正在处理的元素在数组中的索引。 array 调用了 fi...
使用filter() 和map() 会遍历数组两次,但是你可以使用 reduce() 只遍历一次并实现相同的效果,从而更高效。(如果你喜欢使用 for 循环,你可以在遍历一次时使用 forEach() 进行过滤和映射。) jsCopy to Clipboard const numbers = [-5, 6, 2, 0]; const doubledPositiveNumbers = numbers.reduce((accumulator...
jsCopy to Clipboard // 在网页浏览器中,window 对象也是全局对象: console.log(this === window); // true this.b = "MDN"; console.log(window.b); // "MDN" console.log(b); // "MDN" 如果源代码作为模块加载(对于 HTML,这意味着在 标签中添加 type="module"),在顶层,this 总是undefined...
jsCopy to Clipboard const numbers = [1, 2, 3, 4]; const filteredNumbers = numbers.map((num, index) => { if (index < 3) { return num; } }); // index 从 0 开始,因此 filterNumbers 为 1、2、3 和 undefined。 // filteredNumbers 是 [1, 2, 3, undefined] // numbers 依旧是 ...
Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on iOS Samsung Internet WebView Android WebView on iOS Deno Node.js filter Legend Tip: you can click/tap on a cell for more information. Full support Full support...
{ 95 // If no search term has been entered, just make the finalGroup array equal to the categoryGroup 96 // array — we don't want to filter the products further — then run updateDisplay(). 97 if(searchTerm.value.trim() === '') { 98 finalGroup = categoryGroup; 99 update...