②js中,数组长度可以动态改变。 ③接着上述代码,typeof arr 和 arr instanceof Array 分别输出object和true。 代码语言:javascript 代码运行次数:0 运行 AI代码解释 console.log(typeof(names));//objectconsole.log(namesinstanceofArray);//trueconsole.log(""instanceofString);//false 不是对象类型console.log...
AI代码解释 console.log([]instanceofArray);//truefunctionStudent(){}//定义构造函数vartom=newStudent();//实例化一个Student对象console.log(tominstanceofStudent);//trueconsole.log(tominstanceofObject);//trueconsole.log(tominstanceofNumber);//false 输出结果如图1-3所示。 图1-3 instanceof运算符示例...
regs.push(new Array("item_1","^[\\s\\S]+$","item_1Span","法人代表不能为空","填写正确",true)); regs.push(new Array("item_2","^[\\s\\S]+$","item_2Span","开户银行不能为空","填写正确",true)); regs.push(new Array("item_3","^[\\s\\S]+$","item_3Span","帐号...
Well you can write a function that takes the array and the item you’re checking for, but it’s much cleaner to add the contains( item ) method to the Array object. Extending JavaScript Arrays /** * Array.prototype.[method name] allows you to define/overwrite an objects method * needle...
Array.prototype.contains = function (obj) { return this.indexOf(obj) != -1; }; Array.prototype.copy = function (obj) { return this.concat(); }; Array.prototype.insertAt = function (obj, i) { this.splice(i, 0, obj); }; Array.prototype.insertBefore = function (obj, obj2) { va...
** String.prototype.match()方法返回通过一个正则表达式匹配到的字符串结果。** varparagraph='The quick brown fox jumps over the lazy dog. It barked.'; varregex=/[A-Z]/g; varfound=paragraph.match(regex); console.log(found); // 输出: Array ["T", "I"] ...
includes()Check if an array contains the specified element indexOf()Search the array for an element and returns its position isArray()Checks whether an object is an array join()Joins all elements of an array into a string keys()Returns a Array Iteration Object, containing the keys of the ...
Write a JavaScript function to find an array containing a specific element. Test data : arr = [2, 5, 9, 6]; console.log(contains(arr, 5)); [True] Click me to see the solution 33. Empty Array Write a JavaScript script to empty an array while keeping the original. ...
functionstringToArray(str){returnArray.from(str);} 29、检查字符串是否为空或仅由空格组成: functionisStringEmpty(str){returnstr.trim().length ===0;} 30、检查值是否为布尔值: functionisBoolean(value){returntypeofvalue ==='boolean';}
constcontainsSubstring=(string,substring)=>string.includes(substring); 使用includes()方法,我们可以快速判断一个字符串是否包含特定的子字符串。 8. 查找数组中的最大数字: constmaxNumber=array=>Math.max(...array); 使用扩展运算符和 Math.max() 方法,我们可以轻松找到数组中的最大数字。