Substitution of "with" operator in strict mode

Question

Substitution of "with" operator in strict mode

Let's say I have a user-entered string value stored in the variable f. For example:

f = "1/log(x)";

In vanilla JavaScript, I used the following operator:

f = "with (Math) {" + f + "}";

While this code worked perfectly fine in vanilla javascript, it caused issues when I switched to Vue.js and enabled strict mode. I'm not sure how to replace this operator now. Has anyone encountered this problem before and found a solution?

I tried the following approach:

            let math = Math
            math.f = f
            console.log(f)

Unfortunately, nothing seems to be working.

javascript vue.js

Answer 1

Answer №1

It's generally advised against using the 'with' statement as it can lead to problems in programs. So, what other options do you have?

You could define a series of global variables.

const sqrt = Math.sqrt
const log = Math.log

const test1 = new Function("a","return sqrt(a)")
const test2 = new Function("b","return log(b)")

console.log(test1(4))
console.log(test2(100))

Another option is to make replacements using regular expressions.

const fixMath = eq => eq.replace(/(sqrt|log|pow)/g,'Math.$1')

const test1 = new Function("a", fixMath("return sqrt(a)"))
const test2 = new Function("b", fixMath("return log(b)"))
const test3 = new Function("a", "b", fixMath("return pow(a, b)"))
const test4 = new Function("a", "b", fixMath("return sqrt(pow(a, 2) + pow(b, 2))"))

console.log(test1(4))
console.log(test2(100))
console.log(test3(10, 3))
console.log(test4(3, 3))

Answer 2

It's generally advised against using the 'with' statement as it can lead to problems in programs. So, what other options do you have?

You could define a series of global variables.

const sqrt = Math.sqrt
const log = Math.log

const test1 = new Function("a","return sqrt(a)")
const test2 = new Function("b","return log(b)")

console.log(test1(4))
console.log(test2(100))

Another option is to make replacements using regular expressions.

const fixMath = eq => eq.replace(/(sqrt|log|pow)/g,'Math.$1')

const test1 = new Function("a", fixMath("return sqrt(a)"))
const test2 = new Function("b", fixMath("return log(b)"))
const test3 = new Function("a", "b", fixMath("return pow(a, b)"))
const test4 = new Function("a", "b", fixMath("return sqrt(pow(a, 2) + pow(b, 2))"))

console.log(test1(4))
console.log(test2(100))
console.log(test3(10, 3))
console.log(test4(3, 3))

Substitution of "with" operator in strict mode

Answer №1

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