Set javascript parameter inside function

Question

How to set variable which I pass to a function

function checkSetName(inputVar, outputVar, txt){
            if (inputVar.length) {
                outputVar = txt + ': ' + inputVar.val();
            } else {
                outputVar = "";
            }
        }
checkSetName(name, nameTxt, 'Hello world ');

I pass the empty variable nameTxt and I expect it to be set the value inside of function, but after function executes the variable is undefined

How to set variable that I pass to a function in JavaScript

You are missing the return and you should remove the outpuVar because it's useless. — Federico Navarrete
– Federico Navarrete, Commented Feb 7, 2018 at 12:53

georg · Accepted Answer · 2018-02-07 12:50:13Z

8

You can't because JS is a strictly pass-by-value language, there are no ByRef parameters. Just return a value.

function checkSetName(inputVar, txt){
        if (inputVar.length) {
            return txt + ': ' + inputVar.val();
        } else {
            return  = "";
        }

Another (worse) option is to pass an object and modify its state:

function checkSetName(inputVar, state, txt){
        if (inputVar.length) {
            state.output = txt + ': ' + inputVar.val();
        } else {
            state.output = "";
        }

Finally, you can make your a function a method and modify this instead of a parameter object:

class Validations {
    checkSetName(inputVar, txt){
        if (inputVar.length) {
            this.output = txt + ': ' + inputVar.val();
        } else {
            this.output = "";
        }
}

answered Feb 7, 2018 at 12:50

georg

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PSK Over a year ago

Really liked the ways answer is evolving :)

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