What's the best way to convert a number to a string in JavaScript? [closed]

Answer 1

The below are the methods to convert a Integer to String in JS

The methods are arranged in the decreasing order of performance.

(The performance test results are given by @DarckBlezzer in his answer)

var num = 1

Method 1:

num = `${num}`

Method 2:

num = num + ''

Method 3:

num = String(num)

Method 4:

num = num.toString()

Note: You can't directly call toString() on a number. 2.toString() will throw Uncaught SyntaxError: Invalid or unexpected token.

Answer 2

If you need to format the result to a specific number of decimal places, for example to represent currency, you need something like the toFixed() method.

number.toFixed( [digits] )

digits is the number of digits to display after the decimal place.

Answer 3

I think it depends on the situation but anyway you can use the .toString() method as it is very clear to understand.

Answer 4

I'm going to re-edit this with more data when I have time to, for right now this is fine...

Test in nodejs v8.11.2: 2018/06/06

let i=0;
    console.time("test1")
    for(;i<10000000;i=i+1){
    	const string = "" + 1234;
    }
    console.timeEnd("test1")
    
    i=0;
    console.time("test1.1")
    for(;i<10000000;i=i+1){
    	const string = '' + 1234;
    }
    console.timeEnd("test1.1")
    
    i=0;
    console.time("test1.2")
    for(;i<10000000;i=i+1){
    	const string = `` + 1234;
    }
    console.timeEnd("test1.2")
    
    i=0;
    console.time("test1.3")
    for(;i<10000000;i=i+1){
    	const string = 1234 +  '';
    }
    console.timeEnd("test1.3")
    
    
    i=0;
    console.time("test2")
    for(;i<10000000;i=i+1){
    	const string = (1234).toString();
    }
    console.timeEnd("test2")
    
    
    i=0;
    console.time("test3")
    for(;i<10000000;i=i+1){
    	const string = String(1234);
    }
    console.timeEnd("test3")
    
    
    i=0;
    console.time("test4")
    for(;i<10000000;i=i+1){
    	const string = `${1234}`;
    }
    console.timeEnd("test4")
    
    i=0;
    console.time("test5")
    for(;i<10000000;i=i+1){
    	const string = 1234..toString();
    }
    console.timeEnd("test5")
    
    i=0;
    console.time("test6")
    for(;i<10000000;i=i+1){
    	const string = 1234 .toString();
    }
    console.timeEnd("test6")

output

test1: 72.268ms
test1.1: 61.086ms
test1.2: 66.854ms
test1.3: 63.698ms
test2: 207.912ms
test3: 81.987ms
test4: 59.752ms
test5: 213.136ms
test6: 204.869ms

Answer 5

If you are curious as to which is the most performant check this out where I compare all the different Number -> String conversions.

Looks like 2+'' or 2+"" are the fastest.

https://jsperf.com/int-2-string

Answer 6

We can also use the String constructor. According to this benchmark it's the fastest way to convert a Number to String in Firefox 58 even though it's slower than " + num in the popular browser Google Chrome.