SOURCE

Array.prototype.includes = Array.prototype.includes || function
includes(value,start) {
    let ctx = this
    let length = ctx.length
    start = parseInt(start)
    if(isNaN(start)) {
        start = 0
    }else if(start < 0) {
        start = -start > length?0:(length + start)
    }
    let inde想= ctx.indexOf(value)
    return index >= start
}