How to concatenate two numbers in javascript

Question

I d like for something like 5   6 to return  56  instead of 11

User · Answer

You can return a number by using this trick  not recommended   a    b - 0   Example    let output    5    6 - 0  console log output      56 console log typeof output      number

User · Answer

Another possibility could be this   var concat   String 5    String 6

User · Answer

This is the easy way to do this var value   5    quot  quot    6

User · Answer

You can now make use of ES6 template literals   const numbersAsString      5   6    console log numbersAsString      Outputs 56   Or  if you have variables    const someNumber   5  const someOtherNumber   6  const numbersAsString      someNumber   someOtherNumber     console log numbersAsString      Outputs 56   Personally I find the new syntax much clearer  albeit slightly more verbose

User · Answer

Use      5   6 to force it to strings  This works with numerical variables too    x000D   x000D  var a   5  x000D  var b   6  x000D  console log      a   b   x000D   x000D   x000D

User · Answer

simple answer   5        6

User · Answer

I d prefer the concat way    const numVar1   5  const numVar2   6  const value      concat numVar1  numVar2      or directly with values const value2      concat 5  6     You can also use an array which can help in some use cases    const value3    5  6  numVar1  join

User · Answer

enter code here var a   9821099923  var b   91  alert   quot  quot    b   a       after concating   result is 919821099923 but its is now converted into string    console log Number isInteger  quot  quot    b   a       false     you have to do something like this  var c  parseInt  quot  quot    b   a  console log c      919821099923 console log Number isInteger c      true

User · Answer

To add to all answers above I want the share the background logic  Plus is an addition operator that is also used for concatenation of strings  When we want to concatenate numbers  It should be the understanding that we want to concatenate the strings  as the concatenation of numbers doesn t make valid use cases to me  We can achieve it in multiple ways  Through type conversion let a   5  a toString   5    Output 55 type  quot string quot   This will also work and doing type conversion in the background  5   quot  quot   5    Output 55 type  quot string quot   If you are determined to concatenate two string and type of output should be int  parseInt   works here parseInt 5   quot  quot   5     Output 55 Type  quot number quot

User · Answer

Use   var value        5   6    to force it to strings

User · Answer

You can also use toString function to convert it to string and concatenate   var a   5  var b   6  var value   a toString     b toString

User · Answer

var value        5   6  alert value

User · Answer

I converted back to number like this    const timeNow        12   45  const openTime   parseInt timeNow  10     output 1245  -- edit --   sorry   for my use this still did not work for me after testing   I had to add the missing zero back in as it was being removed on numbers smaller than 10  my use is for letting code run at certain times May not be correct but it seems to work  so far    h   new Date   getHours    m   new Date   getMinutes    isOpen  boolean   timeNow    this m  lt  10         this h   0   this m        this h   this m   openTime   parseInt this timeNow     closed       this openTime  gt   1450  amp  amp  this openTime  lt   1830    this isOpen   true    this isOpen   false   this openTime  gt   715  amp  amp  this openTime  lt   915    this isOpen   true    this isOpen   false       The vote down was nice thank you     I am new to this and come here to learn from you guys an explanation of why would of been nice   Anyways updated my code to show how i fixed my problem as this post helped me figure it out

User · Answer

just use   5        6

User · Answer

var output   5        6

User · Answer

I know this is an old post and has been answered many times  I too was wondering if JavaScript had a function that would do this  I was doing some math programming and needed to concatenate two numbers   So the what if I needed to combine two numbers 17 and 29  Sure I can turn them into strings and concatenate them then turn the new string back into a number  That seems to work pretty well and I can go on with my code  but lets take a look here and try to figure out what is really happening here   What are we doing to these two numbers  how do we take 17 and 29 and turn it into one thousand seven hundred and twenty-nine  Well we can multiply 17 by 100 then add 29  And how about 172 and 293 to get one hundred seventy-two thousand two hundred and ninety-three  Multiply 172 by 1000 and add 293  But what about only 2 and 9  Multiply 2 by 10 then add 9 to get 29   So hopefully by now a pattern should be apparent to you  We can devise a math formula to do this calculation for us rather than just using strings  To concatenate any two numbers  a and b  we need to take the product of a and 10 to the power of length b then add b   So how do we get the length of number b  Well  we could turn b into a string and get the length property of it       a   Math pow 10  new String b  length    b    But there has to be a better way to do this without strings  right  Yes there is     For any two numbers  a and b  with any base B  We are going to multiply a by base B to the power of length b  using log base of b then flooring it to get the nearest whole number then adding 1 to it  then adding b   So now our code looks like this       a   Math pow 10  Math floor Math log10 b     1    b    But wait  what if I wanted to do this in base 2 or base 8  How can I do that  We can t use our formula that we just created with any other base but base 10  The JavaScript Math object already has built-in functions for base 10 and 2  just Math log   but how do we get log functions for any other base  We divide the log of b by the log of base  Math log b    Math log base    So now we have our fully functioning math based code for concatenating two numbers       function concatenate a  b  base            return a   Math pow base  Math floor Math log b    Math log base     1    b            var a   17  var b   29      var concatenatedNumber   concatenate a  b  10          concatenatedNumber   1729   If you knew you were only going to be doing base 10 math  you could add a check for base is undefined then set base   10       function concatenate a  b  base            if typeof base     undefined                 base   10                    return a   Math pow base  Math floor Math log b    Math log base     1    b             var a   17  b   29      var newNumber   concatenate a  b      notice I did not use the base argument        newNumber   1729   To make it easier for me  I used the prototype to add the function to the Number object       Number prototype concatenate   function b  base            if typeof base     undefined                     base   10                    return this   Math pow base  Math floor Math log b    Math log base     1    b             var a   17      var newNumber   a concatenate 29          newNumber   1729

[javascript] How to concatenate two numbers in javascript?

Examples related to javascript