您告诉函数sayHello使用call方法,将执行上下文的起始点分配给 characters 对象,并将一个参数列表传递给sayHello函数,在那里它可以正确执行。在本例中,您只传递了一个。apply方法非常类似。最大的区别是apply方法需要一个数组。sayHello(firstName, secondName, thirdName){ console.log(this.message, firstName); //re...
A conforming implementation of this International standard shall interpret characters in conformance with the Unicode Standard, Version 3.0 or later and ISO/IEC 10646-1 with either UCS-2 or UTF-16 as the adopted encoding form, implementation level 3. If...
Write a JavaScript program to produce a new string that has the first 3 characters in lower case from a given string. If the string length is less than 3 convert all the characters to upper case. The program converts the first three characters of a given string to lowercase if the string...
()Join two arrays - concat()Join three arrays - concat()Add an element to position 2 in an array - splice()Convert an array to a string - toString()Add new elements to the beginning of an array - unshift()Remove the first element of an array - shift()Select elements from an array...
During conversion parseInt() will remove any leading whitespace characters. You don't need to do that to the string before parsing it. Note also that parseInt() may only interpret the leading portion of a string. As soon as it encounters an invalid integer numeric character it will assume ...
JavaScript String Length Thelengthproperty returns the length of a string: Example lettext ="ABCDEFGHIJKLMNOPQRSTUVWXYZ"; letlength = text.length; Try it Yourself » Extracting String Characters There are 4 methods for extracting string characters: ...
You can use the slice() method to get the last N characters of a string in JavaScript, passing -n as a negative start index. For example, str.slice(-2) returns a new string containing the last 2 characters of the string. const str = 'JavaScript' const last2 = str.slice(-2) ...
functionisObject(value){returntypeofvalue==='object'&&value!==null;} 20、检查字符串是否包含特定子字符串: functioncontainsSubstring(str, substring){returnstr.includes(substring);} 21、生成指定长度的随机字母数字字符串: functiongenerateRandomAlphanumeric(...
conststr="JavaScript is Awesome";//convert to an array of single characters.str.split("");// returns ["J", "a", "v", "a", "S", "c", "r", "i", "p", "t", " ", "i", "s", " ", "A", "w", "e", "s", "o", "m", "e"]//convert to an array of words...
Although c may look like a number to us, it is actually a string, because it is surrounded by quotation marks. Remember our first call to the alert method where we supplied the text to be displayed? It was written inside of quotation marks, because it was text. You can use either ...