如何获取字符串的第一个字符？

Question

I have a string, and I need to get its first character.

 var x = 'somestring'; alert(x[0]); //in ie7 returns undefined

How can I fix my code?

Answer 1

What you want is charAt .

var x = 'some string';
alert(x.charAt(0)); // alerts 's'

Answer 2

In JavaScript you can do this:

 const x = 'some string'; console.log(x.substring(0, 1));

Answer 3

You can use any of these.

There is a little difference between all of these So be careful while using it in conditional statement.

var string = "hello world";
console.log(string.slice(0,1));     //o/p:- h
console.log(string.charAt(0));      //o/p:- h
console.log(string.substring(0,1)); //o/p:- h
console.log(string.substr(0,1));    //o/p:- h
console.log(string[0]);             //o/p:- h


var string = "";
console.log(string.slice(0,1));     //o/p:- (an empty string)
console.log(string.charAt(0));      //o/p:- (an empty string)
console.log(string.substring(0,1)); //o/p:- (an empty string)
console.log(string.substr(0,1));    //o/p:- (an empty string)
console.log(string[0]);             //o/p:- undefined

Answer 4

 const x = 'some string'; console.log(x.substring(0, 1));

Answer 5

Example of all method

First : string.charAt(index)

Return the caract at the index index

 var str = "Stack overflow"; console.log(str.charAt(0));

Second : string.substring(start,length);

Return the substring in the string who start at the index start and stop after the length length

Here you only want the first caract so : start = 0 and length = 1

 var str = "Stack overflow"; console.log(str.substring(0,1));

Alternative : string[index]

A string is an array of caract. So you can get the first caract like the first cell of an array.

Return the caract at the index index of the string

 var str = "Stack overflow"; console.log(str[0]);

Answer 6

var x = "somestring"
alert(x.charAt(0));

The charAt() method allows you to specify the position of the character you want.

What you were trying to do is get the character at the position of an array "x", which is not defined as X is not an array.

Answer 7

您甚至可以使用slice截断所有其他字符：

x.slice(0, 1);

Answer 8

var str="stack overflow";

firstChar  = str.charAt(0);

secondChar = str.charAt(1);

Tested in IE6+ , FF , Chrome , safari .

Answer 9

也试试这个：

x.substr(0, 1);

Answer 10

Looks like I am late to the party, but try the below solution which I personally found the best solution:

var x = "testing sub string"
alert(x[0]);
alert(x[1]);

Output should show alert with below values: "t" "e"

Answer 11

x.substring(0,1)

Details

substring(start, end) extracts the characters from a string, between the 2 indices "start" and "end", not including "end" itself.

Special notes

• If "start" is greater than "end", this method will swap the two arguments, meaning str.substring(1, 4) == str.substring(4, 1).
• If either "start" or "end" is less than 0, it is treated as if it were 0.

Answer 12

in Nodejs you can use Buffer :

let str = "hello world"
let buffer = Buffer.alloc(2, str) // replace 2 by 1 for the first char
console.log(buffer.toString('utf-8')) // display he
console.log(buffer.toString('utf-8').length) // display 2

Answer 13

你可以这样使用：

'Hello Mr Been'.split(' ').map( item => item.toUpperCase().substring(0, 1)).join(' ');

Answer 14

charAt() do not work if it has a parent prop
ex parent.child.chartAt(0)
use parent.child.slice(0, 1)

Answer 15

You can use any of the following:

let userEmail = "email";
console.log(userEmail[0]); // e
console.log(userEmail.charAt(0)); // e
console.log(userEmail.slice(0, 1)); // e
console.log(userEmail.substring(0, 1)); // e
console.log(userEmail.substr(0, 1)); // e
console.log(userEmail.split("", 1).toString()); // e
console.log(userEmail.match(/./)[0]); // e

Answer 16

Simple Method would be

const z ="sdsdsd"

console.log(z[0])    // 's'

and use pollyfills

Answer 17

It's been 10 years yet no answer mentioned RegExp .

 var x = 'somestring'; console.log(x.match(/./)[0]);

Answer 18

You can use as well:

var x = "somestring";

console.log(x.split("")[0]); // output "s"

This should work with older browsers.

Answer 19

Since every string is an array, probably the most succinct solution is by using the new spread operator:

const x = 'somestring'
const [head, ...tail] = x
console.log(head) // 's'

bonus is you can now access the total string but the first character using join('') on tail :

console.log(tail.join('')) // 'omestring'

Answer 20

For any string str = "Hello World"

str.split(' ').map( item => item.toUpperCase().substring(0, 1)).join(' ');

Output: HW

Answer 21

There are many ways to find the string first character in Javascript. I think the easiest way to find is the string.charAt() method. This method takes an index number as a parameter and returns the index value. If you didn't give any parameter by default its returns the first character of the string.

 const str = "Bangladesh"; const firstCharacter = str.charAt(0); const secondCharacter = str.charAt(1); console.log(firstCharacter) console.log(secondCharacter)

Answer 22

It's been 12 years and just one dev mentioned regexp, but it's a simpler way:

const str = 'string';

str.match(/\w/); // >> s

It will return the first character-class-word from the given string.

Answer 23

in JQuery you can use: in class for Select Option:

$('.className').each(function(){
    className.push($("option:selected",this).val().substr(1));
});

in class for text Value:

$('.className').each(function(){
    className.push($(this).val().substr(1));
});

in ID for text Value:

$("#id").val().substr(1)

Answer 24

var string  = "Hello World";
console.log(charAt(0));

The charAt(0) is JavaScript method, It will return value based on index, here 0 is the index for first letter.