CODEWITHSUNDEEP
javascript
scrblnrd3
scrblnrd3

Reputation: 7416

Javascript unexpected assignment behavior

I'm writing a function to replace all occurrences of variables p and q with their respective values without using eval(), however, I'm running into some unexpected behaviors. BTW, I'm using phpjs for the str_replace

Fiddle: http://jsfiddle.net/5Uedt/2/

function table(str){
    str=str_replace(["nand","nor","implies","equals","not","xor","and","or","(",")"],[" 3 "," 4 "," 5 "," 6 "," 7 "," 8 ", " 9 ", " 10 ", " ( "," ) "],str).replace(/\s{2,}/g, ' ').trim();
    str=str_replace(["3","4","5","6","7","8", "9", "10", "(",")"],["nand","nor","implies","equals","not","xor","and","or","(",")"],str).split(" ");

    var vars={p:1,q:1};
    for(vars['p']=1;vars['p']>=0;vars['p']--){
        for(vars['q']=1;vars['q']>=0;vars['q']--){
            alert(str);
            newinput=str;

            for(var i=0;i<newinput.length;i++){
                var token=newinput[i];
                if(token.length===1){
                    console.log(newinput[i]);
                    newinput[i]=vars[newinput[i]];


                }
            }
//          console.log(n.join(" "));

        }
    }
}

I have this code for replacing all occurrences, but it's not working. I'm alerting the original string entered in every time, however, the string changes. The expected output of the function is p,and,q repeated 4 times, instead, I have p,and,q, then 1,and,1 repeated 3 times. However, I don't seem to have any assignments to str. Does anyone know why this is happening?

Upvotes: 2

Views: 58

Answers (1)

Dan-Nolan
Dan-Nolan

Reputation: 6657

When you set newinput equal to str, you're still referencing that original object. When you change the value later in newinput you affect the str variable.

If you want to clone the object you can iterate over the properties of str like so:

var newinput = {};
for(var key in str) {
    newinput[key] = str[key];
}

Thus making a clone of your original object and you won't be affecting it's values. Assuming you don't have objects you want to clone inside your str object. If you do, just run this function recursively.

Updated Fiddle

Upvotes: 3

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