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Replace specific colours in a webpage with tampermonkey

I am trying to replace all colours on a webpage with my own pre-defined colours. I want to replace all mentions of "rgba(29,161,242,1.00)" with "rgb(255 0 0)" using tampermonkey but I am unsure of how to go about doing it.

Solution

  • If it's a multi-page app with limited JavaScript functionality, this should work:

    const oldColorNormalized = 'rgb(29, 161, 242)'
const newColor = 'rgb(255 0 0)'

document.querySelectorAll('*').forEach(el => {
    if (getComputedStyle(el).color === oldColorNormalized) {
        el.style.color = newColor
    }
})

    If it's a single-page app or has lots of JS-rendered content, you may need something more complex with MutationObservers.