getElementsByTextContent.js

function getLeafElements(root=document.body,result=[]){
    if(root.children.length===0) return result.push(root);
    for(var element of root.children){
        getLeafElements(element,result);
    }
    return result;
}
function getElementsByTextContent(reg){
    var elements=getLeafElements();
    var result=[];
    for(var element of elements){
        if(!(reg instanceof RegExp) && typeof reg === 'string' ) reg=new RegExp(reg);
        if(reg.exec(element.textContent)!==null) result.push(element);
    }
    return result;
}